Sometimes it’s caused by a typo, sometimes it’s cause by a brain freeze, and sometimes it’s caused by a misunderstanding. Misunderstanding possessive pronouns and contractions seems to be a common occurance in writing today. It’s an easy mistake to make, people generally talk using contractions, and these words sound alike. It’s always best to double check them before submitting your work as spell-check will not always catch them. There are two ways to remember these confused words:

Possessive pronouns (his, hers, its) never use apostrophes. Although, possessive nouns do.
Always sound out contractions before using them. Instead of saying “it’s” say “it is.” If the longer version sounds correct, use an apostrophe.

It’s vs. Its

It’s the ugliest dog alive, but its owner is cute.

It’s: a contraction meaning “it is.”: º It’s time for dinner.
Its: a possessive pronoun meaning of or belonging to it. Possessive pronouns (like his, hers, and ours) never use apostrophes.: º The cat was twitching its tail.

They’re vs. Their vs. There

They’re not here right now, but their car is parked over there.

They’re: a contraction meaning “they are.”: º They’re going to be here any minute.
Their: a possessive pronoun meaning of or belonging to them (or they). Possessive pronouns (like his, hers, and ours) never use apostrophes.: º Their house has the tallest tree.
There: Refers to a location. Remember that “here” and “there” are spelled alike.: º The ball is over there.

We’re vs. Were vs. Where

We were going to the store but now we’re lost and don't know where to go.

We’re: a contraction meaning “we are.”: º We’re lost.
Were: past tense of “to be.”: º They were the best dancers at the party.
Where: Refers to a location. Remember that “here” and “where” are spelled alike.: º Where is the ball?

Who’s vs. Whose

Whose turn is to wash dishes and who’s going to take out the trash?

Who’s: a contraction meaning “who is.”: º Who’s at the door?
Whose: a possessive pronoun meaning of or belonging to who or whom. Possessive pronouns (like his, hers, and ours) never use apostrophes.: º Whose coat is this?

You’re vs. Your

Your mother was right; you’re very pretty.

You’re: a contraction meaning “you are.”: º You’re going to be late if you don't hurry.
Your: a possessive pronoun meaning of or belonging to you. Possessive pronouns (like his, hers, and ours) never use apostrophes.: º That dog just stole your shoe.

Affect vs. Effect

Bob hoped to affect the kids positively, but the effect of his efforts wasn't what he hoped.

Affect: (verb) to influence. Although affect can also be a noun, it is usually the word you want if its being used as a verb.: º Lack of sleep affects the quality of your work.
Effect: (noun) consequence, result; (verb) to acomplish. Although effect can be used as a verb, it is usually the word you want if it is being used a noun.: º The effects of smoking on the body has been debated for years.

Advise vs. Advice

She advised us not to drink and drive, then was arrested when she failed to follow her own advice.

Advise: (verb) to offer advice to. Pronounced with a ‘z’ sound.: º Bailey advised Susan not to go to the party.
Advice: (noun) to give an opinion; counsel. Pronounced with an ‘s’ sound.: º Do you have any advice for me?

Breathe vs. Breath

“Don’t breathe a word of this,” she muttered under her breath.

Breathe: (verb) to inhale or exhale air. It is the action you do when taking a breath.: º She understood how to breathe life into her pictures.
Breath: (noun) air inhaled or exhaled. It is what you take when you breathe.: º We were out of breath after running for five miles.

Bathe vs. Bath

A bather bathes in a bath.

Bathe: (verb) the action of taking or giving a bath; To seem to wash or pour over.: º The room was bathed in sunlight.
Bath:(noun) what you take, the water used for cleansing the body. Remember bathtub and bathroom are nouns, not bathetubs or batherooms.: º What time would you like to take your bath?

Clothe vs. Clothes

Parents must feed and clothe their child, but that does not mean the child gets to pick the clothes.

Clothe: (verb) the action of putting on clothes.: º The king was clothed in red and purple silk cloth.
Clothes: (noun) what you wear.: º The clothes really do make the man.

Led vs. Lead

He led the man to the ambush where he was pumped full of lead.

Led: (verb) the past form of the verb “to lead.”: º He led the llama to pasture
Lead: (verb, pronounced “leed”) to guide, to direct.: º In the business world you must lead, follow, or get out of the way.
Lead: (noun, pronounced “led”) a metallic element,: º Superman's X-ray vision can not penetrate lead-lined walls