Overview of quark distributions at Large x

Hadron structure in the large-x regime offers a window on the nonperturbative nature of parton distribution functions (PDFs). It is in the valence region where low-energy models are meaningful, and at x going to 1 where the first principles of QCD guide the shape of the PDFs. It is then tantalizing to explore the large-x region to bridge the perturbative and nonperturbative pictures of QCD. In this talk, we discuss phenomenological efforts towards describing the hadron structure at large x using global QCD analyses, from low to high energy. We review experimental as well as theoretical developments. We expand on the role of first-principle constraints on PDFs in general.