What is the correct way to use an apostrophe in contractions?

What is the correct way to use an apostrophe in contractions?

The correct way to use an apostrophe in contractions is to replace the omitted letters with an apostrophe. For example, "can't" is a contraction of "cannot," where the apostrophe replaces the letters "no." Similarly, "it's" is a contraction of "it is," where the apostrophe replaces the letter "i." The apostrophe always appears before the omitted letters in contractions.