Reserved characters in HTML must be replaced with character entities.
Characters, not present on your keyboard, can also be replaced by entities.
HTML Entities Overview
In SGML, HTML and XML documents, the logical constructs known as character data and attribute values consist of sequences of characters, in which each character can manifest directly (representing itself), or can be represented by a series of characters called a character reference, of which there are two types:
a numeric character reference and a character entity reference. This article lists the character entity references that are valid in HTML and XML documents.
HTML Entities
Some characters are reserved in HTML.
If you use the less than (<) or greater than (>) signs in your text, the browser might mix them with tags.
Character entities are used to display reserved characters in HTML.
A character entity looks like this:
&entity_name;
OR
&#entity_number;
To display a less than sign we must write: < or <
The advantage of using an entity name, instead of a number, is that the name is easier to remember.
The disadvantage is that browsers may not support all entity names, but the support for numbers is good.
Non-breaking Space
A common character entity used in HTML is the non-breaking space:
A non-breaking space is a space that will not break into a new line.
Two words separated by a non-breaking space will stick together at the end of a line. This is handy when breaking the words might be disruptive.
Examples:
- 10
- 10 m/s
- 10 km/h
- 10 PM
Another common use of the non-breaking space is to prevent that browsers truncate spaces in HTML pages.
If you write 10 spaces in your text, the browser will remove 9 of them. To add real spaces to your text, you can use the character entity.
The non-breaking hyphen (‑) lets you use a hyphen character that won't break.
Some Other Useful HTML Character Entities
| Result | Description | Entity Name | Entity Number |
|---|---|---|---|
| non-breaking space | |   | |
| < | less than | < | < |
| > | greater than | > | > |
| & | ampersand | & | & |
| ¢ | cent | ¢ | ¢ |
| £ | pound | £ | £ |
| ¥ | yen | ¥ | ¥ |
| € | euro | € | € |
| © | copyright | © | © |
| ® | registered trademark | ® | ® |
Entity names are case sensitive.
Combining Diacritical Marks
A diacritical mark is a "glyph" added to a letter.
Some diacritical marks, like grave ( ) and acute ( ) are called accents.
Diacritical marks can appear both above and below a letter, inside a letter, and between two letters.
Diacritical marks can be used in combination with alphanumeric characters, to produce a character that is not present in the character set (encoding) used in the page.
Here are some examples:
You will see more HTML symbols in the next chapter of this tutorial.