You probably know that changes to the Constitution are called "amendments." There have been 27 amendments to the Constitution.

There have been 27 amendments to the Constitution.
Here is a very quick overview of the first ten amendments to the Constitution. For a more detailed explanation of each amendment in the Bill of Rights, see What Is the Purpose of the Bill of Rights?
So the next time someone asks how many amendments or changes there are to the Constitution, you'll have plenty of information to give them.