learn the rule: its / it's

  • its is a possessive adjective, indicating ownership of or association to, someone or something, when the owner has been previously mentioned or is easily identified
    • Its sock is green.
    • Where is its potato?
  • it's is a contraction (combination) of it and is and means it is
    • Do you know what it's doing?
    • It's stupid.
  • The two are not interchangeable.
  • Getting it wrong makes you look stupid. And ugly.