Its is the #1 misspelled word in the English language! People use the word it's when they should be using its. Why? People make the boneheaded assumption that if the possessive form of John is John's, and if the possessive form of cat is cat's, then the possessive form of it must be it's. Not so! It's is a contraction for the words 'it is'. What does this mean? It means that a contraction is being used as a possessive pronoun! It is only through awareness of this error that it can be overcome. Make thorough note of what is being discussed, then, and the next time you are called upon to express it in its possessive form, remember to simply leave out the apostrophe by spelling the word as its, and in doing so practice the proper grammar the world likes to see. Thank you.

Note: I could, but I won't for the sake of reasonableness of attitude, comment on the downright mindless usage of the terms there, their, and they're!! The use of proper grammar is a virtue.