Internal spin structure of the proton from high energy polarized e-p scattering

A review is given of our experimental knowledge of the spin dependent structure functions of the proton, which is based on inclusive high energy scattering of longitudinally polarized electrons by longitudinally polarized protons in both the deep inelastic and resonance regions, and includes preliminary results from our most recent SLAC experiment. Implications for scaling, sum rules, models of proton structure, and the hyperfine structure interval in hydrogen are given. Possible future directions of research are indicated.