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.
To display a less than sign(<) we must write:< or <
Character Entity Reference Chart:
<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title> Entities</title> </head> <body> <p> some text</p> <p> some   text</p> <p>4 < 5</p> <p> Facebook ©</p> </body> </html>