I sometimes notice a CSS or JS code surrounded with <![CDATA[ and ]]> tags. I couldn't find any explanation to this. What does CDATA do? Why is it used by some people and what is it needed for?
It tells the interpreter that it should not try to interpret the data enclosed in the tags. For example, if you want a XML file to contain a comment with < or >, XML interpreters will report the file as invalid because the caracters < and > will not be part of standard tag. You simply have to surround the code with the CDATA tags.