Homophones are words that sound alike but are spelled differently (and have different meanings). These words are commonly misused (one used instead of the other). Here are some examples. Well, not all these examples are true homophones (for example, the last pair), but they’re still commonly misused.

loose: Not tight, fastened, contained, or restrained.
Correct: The chimney has a few loose bricks. My shoes are too loose.
Incorrect: If we don’t try harder, we’ll loose the race.

lose: To fail to win. To rid oneself of. Misplace.
Correct: I always lose my car keys. I want to lose ten pounds by summer.
Incorrect: That shirt was too lose on me.

stationary: Not moving. Not capable of being moved. Unchanging.
Correct: At the gym I usually ride the stationary bike for cardio exercise.
Incorrect: We bought some nice birthday cards at the stationary store.

stationery: Writing paper and envelopes. Writing materials and office supplies.
Correct: The artist designed new school stationery.
Incorrect: As I walked by him, I noticed he was completely stationery, just standing there.

compliment: An expression of praise, admiration, or congratulation. Good wishes.
Correct: Please extend my compliments to your parents on their anniversary.
Incorrect: These chairs compliment the room beautifully.

complement: Something that completes, makes up a whole, or brings to perfection.
Correct: This slice of lime is the perfect complement for my diet soda.
Incorrect: I’ve received many complements on my new outfit.

allot: To parcel out, distribute, or apportion. To allocate.
Correct: We will allot 30 minutes to each speaker on the panel.
Incorrect: I really like her allot.

a lot: Very many, a large number. Very much.
Correct: A lot of people are coming to the party.
Incorrect: They will a lot the land to the homesteaders.