Even if these words all have something to do with being sure, they are easily confused.

  • Assure means to tell someone that something will happen or that something is definitely true.

My doctor has assured me that I will be able to read without glasses after my surgery.

  • To reassure somebody means to  make them feel less worried or frightened about a problem.

They reassured us that they would look into the matter.

  • Ensure means to make sure that something will (or will not) happen.

Please ensure that all windows are closed and all doors are locked before you leave the building.

  • Insure means to buy insurance to protect against something bad happening to you or your possessions.

You’d better insure your gear before you go hiking in the mountains.

A man wearing a large rucksack is hiking in the mountains. The image illustrates the idea of insuring gear before doing something adventurous.
You’d better insure your gear before you go hiking in the mountains