IT'S is the contraction of IT IS and IT HAS:

•It's raining(It is raining.)

•It's been raining(It has been raining.)

ITS is a possessive pronoun used to show ownership(possession):

Bingo wagged its tail.

ITS shows that the tail belongs to Bingo.

A contraction is a word with omitted letters replaced by an apostrophe.

A pronoun is used to replace a noun in a sentence.

Possessive pronouns are used to show ownership.(hers, his, theirs, yours, its)

TAKE AWAY: " Everything has its beauty, but not everyone sees it."

---Andy Warhol