[en] To a large extent, the nuclear force is a two body force, so the two body problem is the central problem of nuclear physics. As the only two nucleon bound state, the deuteron has been the object of intense experimental and theoretical interest for four decades. Yet, our knowledge of this simplest of all nuclei is far from satisfactory. Many of its properties have been measured to great precision. To date, our understanding of its structure has remained much less precise. (author)