The three words, assure, ensure, and insure, are often confused. All three words share an element of making an outcome sure. However, rather than using these words interchangeably, I'd like to point out the unique aspects of each word so that you can use them to communicate your intention clearly. Assure is to promise or say with confidence. It is more about saying than doing. Example: I assure you that you’ll be warm enough. Ensure is to do or have what is necessary for success. Example: These blankets ensure that you’ll be warm enough. Insure is to cover with an insurance policy.