The difference between "assure," "ensure," and "insure"

Although these three often show up at the same party to give out hugs, they are not the same thing. "To assure" means to convince, inform positively or give confidence to, "to ensure" means to make something certain to happen, and "to insure" means to make sure you're financially secure. Does that make sense? Do you understand it now, and are you sure about that?

"To assure" vs "to ensure"

"To assure" means to remove doubt or to tell someone something confidently. It is usually followed by an object, i.e., you are giving someone assurance.

You can also tell someone they can "rest assured" because you know everything is under control:

• "Rest assured that Brazil will have a great World Cup in 2014," Rebelo said. (Washington Post)
• "I assure you I meant no harm." (V for Vendetta)
• He considered retirement before doctors assured him he could still fight. (Newsweek)

On the other hand, "to ensure" means to make sure that something happens or is definite:

• Aides said the leaders conferred by telephone to ensure that their speeches, while different in tone, would not be incompatible. (Reuters)

• Roast the Brussels sprouts on a sheet pan for 12 to 15 minutes, shaking the pan about halfway through to ensure even cooking. (New York Times)
• "The "feed kids first" policy is designed to ensure that parents can eat in peace. (New York Times)

"To insure" and its use in financial contexts

Lastly, use "insure" when you need insurance. "To insure" means to arrange financial compensation for the loss of something, or in case someone is injured or dies. You could insure your health, your Cadillac, your condo at the beach, or your stocks and bonds:

• "Very well then, listen: you know our house was insured for a good deal of money - fifteen thousand dollars." (Gabrielle Emile)
• "Euro-area finance chiefs meeting tonight will also discuss using the European Financial Stability Facility to insure bonds of troubled governments." (Business Week)
• "Remarkably, younger and healthier individuals in other industrialized countries have long accepted the agreement to be insured in return for community-rated premiums and guaranteed issue." (New York Times)

Sometimes people say "ensure" or "insure" when they actually mean "assure," to avoid doubt or confusion. Bryan Garner points out in Garner's Modern American Usage that this usage has become ubiquitous.

Oh, dear! We assure you that there is a difference, and by reading this article, you have ensured that you know your way around these tricky words, but unfortunately, we cannot insure you. It's just not that kind of party.