Medicine cabinets come in two forms: recessed or surface mounted. The first is called recessed, meaning the cabinet has a built-in look, flush with your wall. In order to have recessed medicine cabinets, you have to plan a bit more so that you can cut into your wall without hitting any plumbing or other object hidden behind the wall.  The second is called surface mounted or surface mount. This looks bigger even though the cabinet is the same size because the whole structure gets mounted to your wall. It is a lot easier to plan for these; you do not have to cut into the wall, and it might be your only option, especially if you rent.