Reserved characters in HTML must be replaced with character entities.
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 <
    Advantage of using an entity name: An entity name is easy to remember.
The disadvantage of using an entity name: Browsers may not support all entity names, but the support for entity
    numbers is good.
  
Non-breaking Space
A commonly used entity 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 (not break into a new line). This is handy when breaking the words might be disruptive.
Examples:
- § 10
- 10 km/h
- 10 PM
Another common use of the non-breaking space is to prevent browsers from truncating 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.
Tip: The non-breaking hyphen (‑) is used to define a hyphen character (‑) that does not break into a new line.
Some Useful HTML Character Entities
| Result | Description | Entity Name | Entity Number | 
|---|---|---|---|
| non-breaking space |   |   | |
| < | less than | < | < | 
| > | greater than | > | > | 
| & | ampersand | & | & | 
| " | double quotation mark | " | " | 
| ' | single quotation mark (apostrophe) | ' | ' | 
| ¢ | cent | ¢ | ¢ | 
| £ | pound | £ | £ | 
| ¥ | yen | ¥ | ¥ | 
| € | euro | € | € | 
| © | copyright | © | © | 
| ® | registered trademark | ® | ® | 
Note: 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 on the page.
Here are some examples:
| Mark | Character | Construct | Result | 
|---|---|---|---|
| ̀ | a | à | à | 
| ́ | a | á | á | 
| ̂ | a | â | â | 
| ̃ | a | ã | ã | 
| ̀ | O | Ò | Ò | 
| ́ | O | Ó | Ó | 
| ̂ | O | Ô | Ô | 
| ̃ | O | Õ | Õ | 
You will see more HTML symbols in the next chapter of this tutorial.
