when or if

When do we use when and if?

Word Explanation Example
when you are sure that something will happen When I'm in Paris, I'll visit you. (I'm sure, that I'm going to Paris.)
if you are not sure that something will happen If I'm in Paris, I'll visit you. (I'm not sure, that I'm going to Paris.)

ATTENTION! – You can both use when and if when you talk about things that happen repeatedly (in generalizations).

  • When you freeze water, it expands.
  • If you freeze water, it expands.