Its vs It's

A lot of people are confused about the difference between its and it's.

Its is a possessive word and is used in contexts where one wishes to refer to a property or possession of a thing. For example:

   The dog chased its tail.
   The computer wrote to its hard drive.

In contrast, it's is an abbreviation for it is. For example:

   It's a nice day today.  -->  It is a nice day.
   It's not fair!          -->  It is not fair.

Here's how to tell which form to use:

Try "it is" in your sentence as a replacement.
If it works, use "it's", otherwise use "its".