It happens to all of us. We're busily writing a letter or email and suddenly we doubt if a word we just typed is the right one for the situation. Personally, I always have a hard time keeping "it's" and "its" straight. Maybe you struggle with "your" and "you're" or "advice" and "advise."

In fact, there are a number of words that commonly confuse lots of people. To help you out, here's a guide to some of the ones that I see most frequently in the editing work that I do.

Its & It's

Its means of or belonging to it.

It's is the contraction of "it is."

It's just amazing the way the dog can sense when its owner is about to come home.

Their & They're

Their means of or relating to them.

They're is the contraction of "they are."

They're flying to Chicago to visit their cousins.

Whose & Who's

Whose means of or relating to whom.

Who's is the contraction of "who is" or "who has."

Whose turn is it to pick up the guest who's arriving on the 2:00 train?

Your & You're

Your means of or relating to you or yourself.

You're is the contraction of "you are."

You're doing a fabulous job sticking to your diet.

Advice & Advise

Advice is a noun that means guidance or counsel.

Advise is a verb that means to counsel or give advice to.

My advice to you is that you advise your staff to answer the telephone promptly.

Complement & Compliment

Complement (as a noun) means something that completes; complement (as a verb) means to complete.

Compliment (as a noun) means praise or a favorable remark; compliment (as a verb) means to praise.

"I would like to compliment the chef," said Ralph, "for the way the flavors of this dish complement each other so perfectly."

Insure, Ensure & Assure

While all 3 of these words relate to guaranteeing that something is true or that something will happen, there are subtle differences in their usages:

Assure means to say, write or confirm the guarantee.

Ensure means to do something to make certain that something happens.

Insure means to guarantee something with insurance or other financial instruments.

"Let me assure you that there's no need to worry," he said. "While your firewall will ensure that hackers don't get into your system, this new policy will insure you against loss in case your system goes down."