Reserved Characters in HTML > PHP

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

 HTML and XHTML processors must support the five special characters listed in the table below:

 Character Entity Number Entity Name Description
 "  " " quotation mark
 '  ' ' (does not work in IE) apostrophe 
 &  & & ampersand
 <  < < less-than
 >  > > greater-than




http://www.w3schools.com/tags/ref_entities.asp