From http://www.w3schools.com (Copyright Refsnes Data)

HTML Character Entities

Reserved characters in HTML must be replaced with character entities.

Character Entities

Some characters are reserved in HTML. For example, you cannot use the greater than or less than signs within your text because the browser could mistake them for markup.

If we want the browser to actually display these characters we must insert character entities in the HTML source.

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 often is easier to remember. However, the disadvantage is that browsers may not support all entity names (while the support for entity numbers is very good).

Non-breaking Space

The most common character entity in HTML is the non-breaking space.

Normally HTML will truncate spaces in your text. If you write 10 spaces in your text HTML will remove 9 of them. To add lots of spaces to your text, use the   character entity.

Try It Yourself

This example lets you experiment with character entities: Try it yourself

Commonly Used Character Entities

Note Entity names are case sensitive!

For a complete reference of all character entities, visit our HTML Entities Reference.

From http://www.w3schools.com (Copyright Refsnes Data)