HTML Character entities

Some characters cannot be used in the HTML code, because these characters may be recognized as HTML code. To display these characters correctly, HTML source is used. These characters are inserted the following way: &#entity_number or &entity_name.
* Important note: it is better to use numbers, than the names. Numbers are widely supported by the browsers, while names can produce occasional problems.
Example:
Non-breaking space is one of the most frequently used entities. HTML removes extra spaces. So, a special entity is used for adding spaces that will be non-removable.
The list of mostly used entities:
HTML 4.0.
HTML styles
HTML head
HTML meta