It’s vs Its

📌 It’s is a contraction of it is or it has. Its is a possessive form.
It’s est la contraction de it is ou it has. Its est un adjectif possessif.

The dog is chasing its tail.

→ Le chien poursuit sa queue.

Are you sure it’s OK for me to ring you so early?

→ Es-tu sûr que c’est correct de t’appeler si tôt ?

It’s rained a lot this week.

→ Il a beaucoup plu cette semaine.