Ensure - to be certain Assure - to provide certainty, to make things calm, to reiterate Insure - to put an object/person under insurance "Ensure/Be sure that you bring your books tomorrow." "He assured me that everything would be ok." "I had to insure my car."

Assure is a transitive verb meaning to inform positively to remove doubt. For example, The attendant assured us the flight was on schedule. I assure you nothing is wrong. Your kindness assured me of your devotion. In most senses, we assure people that their concerns are being addressed Ensure is a transitive verb meaning to make certain or guarantee. To ensure is to make sure that something will (or won’t) happen or be the case. For example, The sunscreen I applied ensures that I will not burn. You must take the proper precautions to ensure your privacy. To ensure that we don’t run out again, I ordered more food. What makes ensure different from the other words is that we only ensure events or states of being; we don’t ensure things