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.^[1]

A character entity looks like this:

&entity_name;

OR

&#entity_number;

To display a less than sign ( < ) we must write: < or <

An HTML entity is a piece of text ("string") that begins with an ampersand ( & ) and ends with a semicolon ( ; ). Entities are frequently used to display reserved characters (which would otherwise be interpreted as HTML code), and invisible characters (like non-breaking spaces). You can also use them in place of other characters that are difficult to type with a standard keyboard.^[2]

Encode

Encode operations converts any reserved character into its character entity equivalent.

Decode

Decode does the reverse job; converting any character entity into its canonical representation.

Links:
Official list of character entities

Sources:
[1] www.w3schools.com/html/html_entities.asp
[2] developer.mozilla.org/en-US/docs/Glossary/Entity