Not all characters that you see on the keyboard are allowed in the body of an HTML document. However, this is logical. If each tag starts with a (<) и заканчивается символом (>), then it is quite logical that these characters cannot be specified inside ordinary text. These characters have special meaning in HTML documents. When the browser sees them it thinks they are HTML tags and tries to interpret them as such.
To solve the problem of adding characters that are prohibited for input in the text of an HTML document, a set of special characters was developed - sequences that replace characters that are prohibited from keyboard input. Characters that are not present on your keyboard can also be replaced with special characters. Each such sequence (mnemonic reference) necessarily begins with an ampersand (&) and ends with a semicolon (;). Between (&) and (;) you can enter:

• special character name (& name;);
• a numeric code that is entered after the ‰ () sign, that is, when typing a special character by specifying its numeric code, you must use the following notation: (& code;);

The numeric code can be represented in decimal or hexadecimal notation.
For example, to display a less than sign (<) мы должны написать: < (symbol name) or & 60;(numeric code in decimal) or & x0003C;(numeric code in hexadecimal system).

Non-breaking space

The main purpose of the non-breaking space () (by non-breaking space) - separate words, but prohibit line breaks in this place. Since the size of the browser window is not constant, the transition to a new line in the paragraph occurs automatically. In this case, the browser will break the line anywhere there is a space or a hyphen. According to the spelling rules, there are language constructs that cannot be torn apart. Non-breaking space designs include, for example:

• surnames with initials;
• em dashes with the word preceding them;
• monosyllabic words followed by a word;
• numbers followed by units.

In these cases, the non-breaking space () is usually used in HTML code. Such a space will look like a normal space, but it ensures that the words between which it appears will, under all circumstances, be on the same line.

• 15 m / s
• 100 km / h

As you already know, in HTML, several consecutive ordinary spaces are replaced with a single space. If you write 10 spaces in the text, the browser will remove 9 of them. To add real spaces in the text, you can use a non-breaking space () .

Quotes.

There are three types of quotation marks in printing: double angle quotation marks or herringbones (""), typographic quotation marks (“”), and handwritten feet (“”). When working with code, you will use straight double quotation marks ("") and single straight quotation marks ("").
By tradition, in Russian, the main type of quotation marks is “Christmas trees”. In HTML, Christmas trees correspond to symbols « and » ... Many publications also use typographic quotation marks and double straight quotation marks instead of "Christmas trees".
The left and right typographic quotation marks match the characters “ and ” respectively, and the bottom left quote is „ .
Direct double quotes match a special character " .

The use of special quotation marks is shown in the following example:

Example: Using Quotes

Hyphen and dash.

In printing, there are three very similar characters to each other: em dash, en dash and hyphen. Of these, there is only one on the computer keyboard - a hyphen. It is he who is usually used in all cases when a hyphen or dash needs to be put in the text. However, you should follow certain punctuation rules regarding the use of these characters.
For example, the hyphen (-) is used only within words or between numbers. An em dash (-) is placed between words in a sentence and separated from these words by spaces. An em dash corresponds to a mnemonic link — ... An em dash (-) is used between numbers without letters or between words that are typed in capital letters, and is also used as a minus sign in mathematical formulas. There is no space between the em dash and the words. An em dash corresponds to a mnemonic link - .

The use of hyphens and dashes is shown in the following example:

Example: Special characters - and -

• Try it yourself "

Time is money...

The web page takes too long to open.
It should load in 2-4 seconds.
Time is money...

List of some popular HTML special characters

Symbol	Description	Mnemonic name	Numeric Code
	non-breaking space
<	less than	<
>	more than	>	>
&	ampersand	&	&
"	straight double quote	"	"
"	apostrophe	"	"
«	left double angle quotation mark	«	«
»	right double angle quotation mark	»	»
‘	left single quote	‘	‘
’	right single quote	’	’
‚	bottom single quote	‚	‚
“	left double quote	“	“
”	right double quote	”	”
„	bottom double quote	„	„
€	euro	€	€
	copyright		©
®	registered trade mark	®	®

Varieties of special characters

On a regular keyboard, you will not find most of the mathematical, technical, geometric and other special characters.
To apply such characters in an HTML page, you can use their corresponding mnemonic names.

In the following example, you can see how the same symbol can be displayed using different codes.

Special characters are technical characters that are not represented on the keyboard and are encoded using UNICOD or other metalanguage encoding. Special characters are divided into groups: mathematical, Greek alphabet, ISO 8859-1 and others. Why they are needed and how to use, read further in the article.

Using special characters when writing documents

The use is carried out for the following purposes:

1. Giving the article completeness and aesthetics. Special signs help you quickly understand the dimensions or read the historical name in Latin or Greek.
2. Several elements provide the correct layout for the document. For example, “” and “” are different, the former are transmitted by standard means, others through special characters.
3. Layout of documents of a mathematical orientation cannot do without knowledge of the main groups of elements.

Basic signs

The material will allow you to find special characters in the appropriate encoding for quick insertion into the text.

Appearance	Designation	Html code	CSS code
☃	snowman	☃	\2603
☦	Orthodox cross	☦	\2626
⚓	Anchor	⚓	\2693
✆	Telephone sign	✆	\2706
☎	Telephone	☎	\ 260E
☕	Hot drinks	☕	\2615
✎	Pencil pointing right and down	✎	\ 270E
✏	Pencil	✏	\ 270F
✐	Pencil pointing right-up	✐	\2710
✑	Open nib	✑	\2711
✒	Shaded nib	✒	\2712
⚜	Heraldic lily	⚜	\ 269C
⛑	Helmet with a white cross	⛑	\ 26D1
⚝	Traced white star	⚝	\ 269D
❄	Snowflake	❄	\2744
❤	Painted over fat heart	❤	\2764
❅	Snowflake trapped by shamrocks	❅	\2745
❆	Bold acute-angled snowflake	❆	\2746
★	Shaded star	★	\2605
☆	Unpainted star	☆	\2606
✪	An open star in a filled circle	✪	\ 272A
✫	A filled star with an open circle inside	✫	\ 272B
✯	Spinning star	✯	\ 272F
❉	Spherical star	❉	\2749
❋	Bold eight-pointed teardrop-shaped propeller star	❋	\ 274B
✲	An asterisk with an open center	✲	\2732
☀	Shaded sun with rays	☀	\2600
☁	Clouds	☁	\2601
☂	Umbrella	☂	\2602
☑	Check mark in the square	☑	\2611
☒	Cross in a square	☒	\2612
☹	Frowning emoticon	☹	\2639
☺	Smiling emoticon	☺	\ 263A
☻	Painted over smiling emoticon	☻	\ 263B
☭	Hammer and sickle	☭	\ 262D
⚑	Painted flag	⚑	\2691
⚐	Unfilled flag	⚐	\2690
☰	Trigram	☰	\2630
✿	Painted flower	✿	\ 273f
❀	Unpainted flower	❀	\2740
✾	Flower with six petals	✾	\ 273E
❁	Filled outlined flower	❁	\2741
❂	Flower of dots	❂	\2742
✉	Envelope	✉	\2709
❦	Heart in the form of a flower	❦	\2766
❶	Number 1	❶	\2776
❷	Number 2	❷	\2777
❸	Number 3	❸	\2778
❹	Number 4	❹	\2779
❺	Number 5	❺	\ 277A
❻	Number 6	❻	\ 277B
❼	Number 7	❼	\ 277C
❽	Number 8	❽	\ 277D
➒	Number 9	➒	\2792
➓	Number 10	➓	\2793
✖	Bold multiplication sign	✖	\2716
✘	Bold cross	✘	\2718
✔	Bold check mark	✔	\2714
✚	Bold cross	✚	\ 271A
⚛	Atom symbol	⚛	\ 269B
♺	Recycling symbol	♺	\ 267A
❑	Unfilled square with lower right shadow	❑	\2751
❒	Unfilled square with upper right shadow	❒	\2752
◈	Rimmed diamond	◈	\ 25C8
◐	Circle with left half filled	◐	\ 25D0
◑	Circle with filled right half	◑	\ 25D1
⁂	Three stars	⁂	\2042

Punctuation marks

Appearance	Designation	Html code	CSS code
<	Less than sign (start of tag)	<	\ 003C
>	Greater than sign (end of tag)	>	\ 003E
«	Left double angle bracket	«	\ 00AB
»	Right double angle bracket	»	\ 00BB
‹	Left angle single quote	‹	\2039
›	Right angle single quote	›	\ 203A
«	Double quote	"	\0022
′	Single stroke	′	\2032
″	Double stroke	″	\2033
‘	Left single quote	‘	\2018
’	Right single quote	’	\2019
‚	Bottom single quote	‚	\ 201A
“	Left double quote	“	\ 201C
”	Right double quote	”	\ 201D
„	Bottom double quote	„	\ 201E
❜	Bold single top comma	❜	\ 275C
❛	Bold single turned top comma	❛	\ 275B
&	Ampersand	&	\0026
‘	Apostrophe (single quote)	"	\0027
§	Paragraph	§	\ 00A7
©	Copyright sign		\ 00A9
¬	Negative sign	¬	\ 00AC
®	Registered trade mark sign	®	\ 00AE
¯	Macron	¯	\ 00AF
°	Degree	°	\ 00B0
±	Plus or minus	±	\ 00B1
¹	Superscript "1"	¹	\ 00B9
²	Superscript "2"	²	\ 00B2
³	Superscript "3"	³	\ 00B3
¼	One quarter	¼	\ 00BC
½	A half	½	\ 00BD
¾	Three quarters	¾	\ 00BE
´	Accent mark	´	\ 00B4
µ	Micro	µ	\ 00B5
¶	Paragraph mark	¶	\ 00B6
·	Multiplication sign	·	\ 00B7
¿	Inverted question mark	¿	\ 00BF
ƒ	Florin sign	ƒ	\0192
™	Trade mark sign	™	\2122
	List marker	.	\2022
…	Ellipsis	…	\2026
‾	Overline	‾	\ 203E
–	Middle dash	-	\2013
-	Em dash	—	\2014
‰	Ppm	‰	\2030
}	Right curly brace	}	\ 007D
{	Left curly brace	{	\ 007B
=	Equal sign	=	\ 003D
≠	Inequality sign	≠	\2260
≅	Congruence (geometric equality)	≅	\2245
≈	Almost equal	≈	\2248
≤	Less than or equal	≤	\2264
≥	Greater than or equal	≥	\2265
∠	Injection	∠	\2220
⊥	Perpendicular (Up Button)	⊥	\ 22A5
√	Square root	√	\ 221A
∑	N-ary summation	∑	\2211
∫	Integral	∫	\ 222B
※	Footnote sign	※	\ 203B
÷	Division sign	÷	\ 00F7
∞	The Infinity symbol	∞	\ 221E
@	Dog symbol	@	\0040
[	Left square bracket	[	\ 005B
]	Right square bracket	]	\ 005D

Arrows

Appearance	Designation	Html code	CSS code
←	Left arrow	←	\2190
	Up arrow		\2191
→	Right arrow	→	\2192
↓	Arrow to down	↓	\2193
↔	Left-right arrow	↔	\2194
↵	Down Arrow and Left Arrow - Carriage Return	↵	\ 21B5
⇐	Double arrow to the left	⇐	\ 21D0
⇑	Double up arrow	⇑	\ 21D1
⇒	Double arrow to the right	⇒	\ 21D2
⇓	Double down arrow	⇓	\ 21D3
⇔	Left-Right Double Arrow	⇔	\ 21D4
➠	Flying arrow	➠	\ 27A0
➤	Arrowhead	➤	\ 27A4
➥	Curved arrow pointing down and to the right	➥	\ 27A5
➦	Curved boom pointing up and to the right	➦	\ 27A6
➳	Arrow to the right	➳	\ 27B3
↺		↺	\ 21BA
↻	Round arrow with a counterclockwise tip	↻	\ 21BB
⇧	Thick hollow up arrow	⇧	\ 21E7
↩	Left arrow with hook	↩	\ 21A9
➫	Downward tilted volumetric arrow	➫	\ 27AB
⬇	Down arrow	⬇	\ 2B07
⬆	Filled up arrow	⬆	\ 2B06

Card suits, zodiac signs and currency icons

Appearance	Designation	Html code	CSS code
♠	"Peaks"	♠	\2660
♣	"Clubs"	♣	\2663
	"Hearts"		\2665
♦	"Diamonds"	♦	\2666
♡	Contour "Hearts"	♡	\2661
♢	Contour "Tambourines"	♢	\2662
♤	Spades contour	♤	\2664
♧	Contour "Clubs"	♧	\2667
¢	Cent	¢	\ FFE0
£	GBP	£	\ FFE1
₽	Russian ruble	₽	\ 20BD
¥	Yen or yuan	¥	\ 00A5
€	Euro	€	\ 20AC
$	Dollar	$	\0024
₴	Hryvnia sign	₴	\ 20B4
₹	Indian rupee	₹	\ 20B9
圓	CNY	圓	\5713
₸	Kazakhstani tenge	₸	\ 20B8
♈	Aries	♈	\2648
♉	Taurus	♉	\2649
♊	Twins	♊	\ 264A
♋	Cancer	♋	\ 264B
♌	a lion	♌	\ 264C
♍	Virgo	♍	\ 264D
♎	scales	♎	\ 264E
♏	Scorpion	♏	\ 264F
♐	Sagittarius	♐	\2650
♑	Capricorn	♑	\2651
♒	Aquarius	♒	\2652
♓	Fishes	♓	\2653

Greek alphabet

Letter	lowercase		uppercase
	symbol	html code	symbol	html code
alpha	α	α	Α	Α
beta	β	β	Β	Β
gamma	γ	γ	Γ	Γ
delta	δ	δ	Δ	Δ
epsilon	ε	ε	Ε	Ε
zeta	ζ	ζ	Ζ	Ζ
this	η	η	Η	Η
theta	θ	θ	Θ	Θ
iota	ι	ι	Ι	Ι
kappa	κ	κ	Κ	Κ
lambda	λ	λ	Λ	Λ
mu	μ	μ	Μ	Μ
nude	ν	ν	Ν	Ν
xi	ξ	ξ	Ξ	Ξ
omicron	ο	ο	Ο	Ο
pi	π	π	Π	Π
ro	ρ	ρ	Ρ	Ρ
sigma	σ	σ	Σ	Σ
ultimate sigma	ς	ς
tau	τ	τ	Τ	Τ
upsilon	υ	υ	Υ	Υ
fi	φ	φ	Φ	Φ
hee	χ	χ	Χ	Χ
psi	ψ	ψ	Ψ	Ψ
omega	ω	ω	Ω	Ω

How to use in practice

Regardless of the CMS, adding an article is done using a visual editor and HTML version. All special characters in the encoding can be inserted only in the second case. To use the tools correctly, it is recommended to take note of the tables that show the code and the external view.

Please note that if you insert a sign in the visual presentation of the article, then the element will turn into the corresponding code in HTML. When entering information manually, be aware of the case, which affects the final result.

Hello dear readers of the blog site! Those who at least superficially managed to get acquainted with, probably already took note, albeit in general terms. This means they have an idea of ​​what HTML characters are generally used in the document code.

In today's article we will try to figure out what a space in HTML is, in which cases it is possible to use whitespace characters when formatting the code itself for easy reading. We will find out when it is necessary to use a non-breaking space, and also get acquainted with other special characters (or, as they are also called, mnemonics).

In fact, I would advise you not to ignore the topic of using various special characters, since this is an important component that allows you to complete the study of the hypertext markup language. In general, the information provided in this publication will definitely not be superfluous. Well, now to the point.

Spaces and whitespace characters in HTML

An important point needs to be made first. The computer keyboard has special keys that allow you to implement text separation (more on this below). However, only a wide space bar provides a section between words not only in the editor, but also in the browser window. There are nuances in line wrapping and margin indentation.

As you know, the display of certain elements in a web browser is determined by tags. To format the text, a well-known one is used, which is block. That is, its content spans across the entire available width.

To wrap lines within paragraph P, you need to use a single BR tag with which you can do this. Let's say we need to insert into the text some lines from a poem that we write in a text editor:

Despite the fact that the lines of the verse are located correctly and the hyphenation is carried out in the right places, in the browser everything will look different:

To achieve the same display in the browser window, you need to write BR in each place of the line break:

Now we have reached the completion of the task, and in the browser the verse lines will be displayed absolutely correctly:

Thus, the required line breaks are completed. Here it is also necessary to note such a feature that multiple spaces, following one after another, are displayed by the web browser as one. You can be convinced of this if in the same editor you try to put not one, but several spaces between two words and, by clicking on the "Save" button, look at the result in a browser.

Space, tab, and line break

Basically, with these whitespace characters we get to know right away how we start working with the text in the editor and format it in the desired form. To implement such a task, there are special keys, each of which corresponds to its own space character:

• Spacebar - the widest key on a computer keyboard (without an inscription);
• Tabulation - the key on the left with the inscription "Tab" and two arrows pointing in different directions;
• Line break - "Enter" key.

However, as I said above, the final desired result, not only in the text editor, but also in the browser, we get only when we use the first key. All three keys (including tabulation and line break are useful when formatting HTML code. For example, this is how a piece of code looks in NotePad ++ (there is a good deal of information about this editor) when all whitespace characters are displayed:

We get code that is easy to read and understand, thanks to the spaces. The orange arrows mark the indentation created using the Tab key, and the CR and LF characters mark line breaks using the Enter kavisha.

Containers nested inside one another are viewed, opening and closing tags are well distinguished. In this form, this code can be easily edited. Now compare it with the same code, which does not have such text splitting:

In the same way, using whitespace characters, you can write CSS rules that will visually look understandable and digestible:

After you bring all the styles to a common denominator and completely finish editing the style file, you can expose by removing all spaces from the code. This is necessary for promotion, which is very important when promoting a resource.

Special characters (or mnemonics) in HTML code

Now we will analyze in what cases it is necessary to use special characters, which I mentioned at the beginning of the article. HTML special characters, sometimes called mnemonics, were introduced to solve a long-standing problem with encodings in the hypertext markup language.

When you type on the keyboard, the characters of the language you are using are encoded. In the web browser, the typed text will be displayed in the fonts of your choice as a result of the reverse decoding operation.

The fact is that there are many such encodings, now we have no goal to parse them in detail. It's just that each of them may lack certain symbols, which, however, need to be displayed. For example, you have an urge to write single quotes or an accent mark, but these icons are trite to be absent from the set.

In order to eliminate this problem, a system of special characters was introduced, which includes a huge number of very different mnemonics. They all begin with an ampersand "&" and usually end with a semicolon ";". At first, each special character had its own digital code. For example, for a non-breaking space, which we will consider in more detail below, the following notation will be valid:

But after a while, the most common symbols were assigned alphabetic counterparts (mnemonics) to make them easier to remember. Let's say for the same non-breaking space it looks like this:

As a result, the browser displays the corresponding symbol. The list of mnemonics is very voluminous, the most commonly used HTML special characters you can find from the following table below:

symbol	code	mnemonics	description
			non-breaking space
			narrow space (en-letter-wide)
			wide space (em-wide in the letter m)
–	-	–	narrow dash (en-dash)
-	—	—	wide dash (em -dash)
­	-	­	soft transfer
a		́	stress, placed after the "stressed" letter
©		©	copyright
®	®	®	registered trade mark
™	™	™	trademark mark
º	º	º	spear of mars
ª	ª	ª	mirror of venus
‰	‰	‰	ppm
π	π	π	pi (use Times New Roman)
¦	¦	¦	vertical dotted line
§	§	§	paragraph
°	°	°	degree
µ	µ	µ	micro sign
¶	¶	¶	paragraph mark
…	…	…	ellipsis
‾	‾	‾	overline
´	´	´	accent mark
№		№	number sign
🔍		🔍	Magnifier (tilted to the left)
🔎		🔎	Magnifier (tilted to the right)
signs of arithmetic and mathematical operations
×	×	×	multiply
÷	÷	÷	divide
<	<		smaller
>	>	>	more
±	±	±	plus / minus
¹	¹	¹	degree 1
²	²	²	degree 2
³	³	³	degree 3
¬	¬	¬	negation
¼	¼	¼	one quarter
½	½	½	a half
¾	¾	¾	three quarters
⁄	⁄	⁄	fractional bar
−	−	−	minus
≤	≤	≤	less than or equal to
≥	≥	≥	more or equal
≈	≈	≈	approximately (almost) equal
≠	≠	≠	not equal
≡	≡	≡	identically
√	√	√	square root (radical)
∞	∞	∞	Infinity
∑	∑	∑	summation sign
∏	∏	∏	work mark
∂	∂	∂	partial differential
∫	∫	∫	integral
∀	∀	∀	for everyone (visible only if in bold)
∃	∃	∃	exists
∅	∅	∅	empty set
Ø	Ø	Ø	diameter
∈	∈	∈	belongs
∉	∉	∉	not belong
∋	∋	∗	contains
⊂	⊂	⊂	is a subset of
⊃	⊃	⊃	is a superset
⊄	⊄	⊄	is not a subset of
⊆	⊆	⊆	is a subset of or equal to
⊇	⊇	⊇	is a superset or equal to
⊕	⊕	⊕	plus in a circle
⊗	⊗	⊗	multiplication sign in a circle
⊥	⊥	⊥	perpendicular
∠	∠	∠	injection
∧	∧	∧	logical AND
∨	∨	∨	logical OR
∩	∩	∩	crossing
∪	∪	∪	Union
currency signs
€	€	€	Euro
¢	¢	¢	Cent
£	£	£	Lb
¤	¤t;	¤	Currency sign
¥	¥	¥	Yen and RMB sign
ƒ	ƒ	ƒ	Florin sign
markers
	.		simple marker
○		○	circle
·	·	·	midpoint
†		†	cross
‡		‡	double cross
♠	♠	♠	peaks
♣	♣	♣	clubs
			hearts
♦	♦	♦	diamonds
◊	◊	◊	rhombus
✏		✏	pencil
✎		✎	pencil
✐		✐	pencil
✍		✍	hand
quotes
"	"	"	double quote
&	&	&	ampersand
«	«	«	left typographic quotation mark (herringbone quotation mark)
»	»	»	right typographic quotation mark (herringbone quotation mark)
‹		‹	single opening angle quotation mark
›		›	single closing angle quotation mark
′	′	′	stroke (minutes, feet)
″	″	″	double prime (seconds, inches)
‘	‘	‘	upper left single quotation mark
’	’	’	upper right single quotation mark
‚	‚	‚	bottom right single quote
“	“	“	quotation mark-foot left
”	”	”	quotation mark-foot upper right
„	„	„	quotation mark-foot right lower
❛		❛	single english opening quotation mark
❜		❜	single English closing quotation mark
❝		❝	open double quotation mark
❞		❞	English double quotation mark closing
arrows
←	←	←	left arrow
			up arrow
→	→	→	right arrow
↓	↓	↓	arrow to down
↔	↔	↔	left and right arrow
↕		↕	up and down arrow
↵	↵	↵	carriage return
⇐	⇐	⇐	double left arrow
⇑	⇑	⇑	double up arrow
⇒	⇒	⇒	double right arrow
⇓	⇓	⇓	double down arrow
⇔	⇔	⇔	left and right double arrow
⇕		⇕	double up and down arrow
▲		▲	triangular up arrow
▼		▼	triangular down arrow
			triangular right arrow
◄		◄	triangular left arrow
stars, snowflakes
☃		☃	snowman
❄		❄	Snowflake
❅		❅	Snowflake trapped by shamrocks
❆		❆	Bold acute-angled snowflake
★		★	Shaded star
☆		☆	Unpainted star
✪		✪	An open star in a filled circle
✫		✫	A filled star with an open circle inside
✯		✯	Spinning star
⚝		⚝	Traced white star
⚪		⚪	Middle open circle
⚫		⚫	Medium filled circle
⚹		⚹	Sextile (like a snowflake)
✵		✵	Eight-pointed rotating star
❉		❉	Spherical star
❋		❋	Bold eight-pointed teardrop-shaped propeller star
✺		✺	Sixteen-pointed asterisk
✹		✹	Twelve-pointed filled star
✸		✸	Bold eight-pointed rectilinear filled star
✶		✶	Six-pointed filled star
✷		✷	Eight-pointed rectilinear shaded star
✴		✴	Eight-pointed filled star
✳		✳	Eight-pointed star
✲		✲	An asterisk with an open center
✱		✱	Bold star
✧		✧	Pointed four-pointed unpainted star
✦		✦	Pointed four-pointed shaded star
⍟		⍟	Star in a circle
⊛		⊛	Snowflake in a circle
clock, time
⏰		⏰	Watch
⌚		⌚	Watch
⌛		⌛	Hourglass
⏳		⏳	Hourglass

Use cases for some special characters, including non-breaking space and soft hyphen

If you have already studied the table a little, then you received confirmation of the words I said above that to display all special characters, a digital code () or its alphabetic analogue (symbolic mnemonic) is used, where letters () are written instead of a combination of a lattice and numbers.

Now let's see when it is necessary to apply these codes. Let's say in an article you need to specify some HTML tag for informational purposes, for example,