I couldn't care less vs I could care less

You could not care less!

What you mean is "I don't care"

When you say "I could care less" you are saying the opposite of what you mean.

Email vs. Emails

There is no such thing as "emails"!

Do you go to the mailbox to see how many "mails" you have? No! Mail is a collective noun, which means that the plural of mail is "mail".

The same applies to the word "email".

If you want to say you have a lot of email, you can say:

Never ever say "emails". It marks you as illiterate, ignorant, and probably an AOL user.

Your and You're

It is so simple:

Their, They're and There

This is another easy one:

Then vs. Than

Then has to do with time, Than is used to compare things:

To - Too - Two

How to use these three words:

Things and Thing's

Those little single-quote marks [ ' ] are called Apostrophes.

When they come in front of an S, they usually show something belongs to someone or something.

Leave out the apostrophe, and the word becomes a plural (meaning there are more than one).

There is one exception to this rule:

Its and It's

1990s and '90s

Another way the apostrophe is misused is in writing the numeric names of decades.

Administrators administer

There is no such word as "administrate". What administrators do is administer.

Mischievous

This word is commonly incorrectly pronounced "mis-cheev-ee-us" especially in the US West and South. That's one more -ee- than the word contains.

The correct pronounciation is mis-cheev-us. .

Height and Width

Another non-word commonly heard in the US West and South is heighth.. The correct spelling is height and the correct pronounciation is "hite". No doubt the error comes from its close association with the word width, which does have a "th" ending. .

Lose vs. Loose

Another easy one:

Lose
1. The opposite of "win" We are going to lose this game
2. The verb for "lost" How could you lose my pen?

Loose
1. The opposite of "tight" He has a screw loose.
2. To set something free If you open the cage door, the bird will get loose.

Yeah and Yay and Yea

This is all over the message boards these days - a disconnect between spelling and pronounciation:

Yay
Rhymes with "way", "pay" and "clay" You say this when you are very happy "Yay for the home team" It's related to "hooray"

Yeah
Rhymes with "there", "pair" and "chair", if you leave out the final "r" Use this to agree with something: "Yeah, i'll do it"
It's also what you might yell when you're happy, fist in the air, "Yeah!"
This usage has only been around for about 20 years, though.

Yea
Rhymes with "way", "pay" and "clay" Two meanings: 1. Yes (the opposite of "Nay") 2. A King James era particle of speech for emphasis ("Yea, verily, I say unto you")

Dominate vs. Dominant

Chalk this up to a lack of attention to detail:

Dominate
It's a verb! Use this to say what the person on top does. "I like a woman to dominate me."

Dominant
This is the adjective - it describes a type of person,place or thing. "He is in search of a dominant woman"
So please don't advertise for "a dominate" on Craig's List. You want "a dominant". Or maybe I do.

Who vs. That

This is so common sense it hurts: People are "who" things are "that"

Who
Use this to talk about people: "There is this guy who peeps in my window all the time."

That
Don't use this word on people! "There is this car that keeps passing by the house."

You want to get into the habit of using "who" when you mean a person. You should also get out of the habit of using "that".

Passed vs. Past

Easily confused because they are pronounced almost the same

Passed
Use this when you are talking about distance: "While I was walking south, I passed this guy on the street walking north."
Also use this when you are talking about test scores: "He scored 80% on the test, so he passed."

Past
It's about time: "I knew him in the past, maybe 10 years ago."