Its v. it’s

Its and it’s are often confused in writing. In speech they sound the same (/ɪts/), so it doesn’t matter.

• Its is the third person neuter possessive determiner pronoun, used as both a dependent possessive determiner though not generally as an independent possessive determiner.
• "it’s" is a contraction of "it is", or sometimes (particularly in speech and informal writing) "it has".

Interestingly the possessive morpheme 's, seems to affect both the change it --> its and Bob --> Bob’s. Historically also it’s was accepted as a pronoun.

Compare also the gender-neutral, indefinite pronoun, "one", the possessive determiners of which are "one’s", not *"ones". A similar problem also occurs between whose and who’s.