What's Causing the Confusion?
"It's" and "its" have the same pronunciation (they are homophones), but different grammatical categories, and therefore different uses in a sentence.
- It's is the contracted (shortened) form of 'it is', or 'it has'.
Possessive Form of 'It'
So, it is understandable if many would think that the possessive form of 'it' should be it's. But the possessive form of 'it' is "its" (with no apostrophes).
Can the Contracted Form Mean 'It Was?'
Although you might hear someone using the contracted form of 'was' in spoken language, but you should know that it is not grammatically correct. Unless there are obvious signs that the sentence is in the past tense, avoid using 's' as a contracted form of 'was'.
- Its is the possessive pronoun of 'it' showing possession or ownership by a thing non-human.
We use apostrophes to show possession for a noun. For example "The captain's" or "the cat's" is the possessive forms of 'captain' and 'cat' (as in 'the captain's boat or the cat's basket).
The dog chased
The car has
Its' is not a word in English language, so do not use this combination EVER.