Your background is the kind of family you come from and the kind of education you have had. It can also refer to such things as your social and racial origins, your financial status, or the type of work experience that you have.

The background to an event or situation consists of the facts that explain what caused it.

The background is sounds, such as music, which you can hear but which you are not listening to with your full attention.

You can use background to refer to the things in a picture or scene that are less noticeable or important than the main things or people in it.