Contractions

We often "contract" or shorten words in English. For example, we may say "he's" instead of "he is". Note that we usually insert an apostrophe (') in place of the missing letter or letters in writing. Here are some example sentences:

I haven't seen him. (I have not seen him.)
Who's calling? (Who is calling?)
They're coming. (They are coming.)

We do this especially when we speak. We do not contract words so much in writing