The history of the modern day Boxer is lengthy and selective. In the early 19th century in Germany, breeders began developing a hunting dog from the Bullenbeisser bloodlines. This dog would be fearless in the face of large game such as bear, boar and bison. Over much continued selective breeding, the modern day boxer is both a fabulous farm dog, guarding and herding cattle, and a common family pet who is very protective in nature.
Boxers are very tough and energetic dogs with a high level of intelligence. They are best suited for families who are committed to doing full on activities and who can provide for their high working drive needs. There are many common behavior problems that are associated with boxers, because when they don't get ample exercise and discipline, this breed tends to become over protective of the wrong things.
They are incredibly loyal and constantly "on watch" for who (or what) they can protect and how. This can be both a wonderful or highly inconvenient trait for families with small children. While they make great guard dogs, they may become like stubborn babysitters of the children and may even become possessive. If you are considering a boxer for a pet, I would highly recommend chatting with several other boxer owners and learning what their experience is.
Boxers are in the working group, meaning they were bred to do a specific job. They were bred to find, protect and be loyal both on the hunt and at home in German farmlands. Therefore, this is not the ideal dog for apartment living or the family looking for a dog with minimal daily exercise or job related needs.
Again, boxers can make fabulous family pets, but they need a fair amount of leadership and clarity of rules, roles, a job and proper exercise. This may simply be carrying a backpack around the neighborhood on the family walk, and set on guard duty in the back yard during the day. I would highly recommend consulting a professional to determine how your lifestyle can blend with a boxer if you are considering owning one or if you already do.