Use "ensure" when you want to provide a guarantee that something is certain or secure.
- To ensure your cooperation, we have posted armed guards throughout the facility.
- "To win the War, to overcome the enemy upon the fields cannot alone ensure the Victory in Peace. The cause of War must be removed." (Haile Selassie I)
Use "insure" when you want to provide a guarantee against a risk of damage or loss. This is generally done through the payment of a premium. It indicates the assumption of liability.
- Tippecanoe Mutual will insure your vehicle for accidental damage or theft.
- "Humankind has become so much one family that we cannot insure our own prosperity except by insuring that of everyone else." (Bertrand Arthur William Russell)
- An example of all three in one sentence: As your representative, I assure you that I will ensure you can insure your home.
- In some instances, "assure" and "ensure" are interchangeable.
- In some instances, "ensure" and "insure" are interchangeable.
- This article is based upon American usage in the United States.