Its and It's (courtesy of the Grammar-Monster)
It's and Its
There is often confusion between its and it's. If you delve deeper into this issue, you will see that there is good reason for the confusion. However, if you just want to know what is right, the matter is very simple.
It's
It's is short for it is or it has. This is a 100% rule. It cannot be used for anything else.
If you cannot expand 'it's' to 'it is' or 'it has', then it is wrong!
Its
Its is like his and her. (They are all possessive adjectives.) Look at these examples:
These are his pies.
(His is used for a masculine possessor (owner).)
These are her flowers.
(Her is used for feminine possessor.)
These are its footprints.
(Its is used for neuter possessor.)