I have find so many words between that but unable to understand when actually used it's and when its. Please explain with example.
In the simplest possible terms:
It's is a contraction of "It is" or (less often) "It has".
Examples: "It's been hot out all week." (Contraction of 'it has'). "It's good to see you again." (Contraction of 'it is')
Its is a possessive, meaning "belonging to it".
Examples: "The company announced its new product today." (The product belongs to the company.) "The government taxes its citizens." (The citizens 'belong to' the government.)
If you're not sure which one to use, try substituting "it is" in the same place. If that makes sense, use "it's". Otherwise, use "its".