Fast ions with energies significantly larger than the bulk ion temperature are used to heat most tokamak plasmas. Fast-ion populations created by fusion reactions, by neutral-beam injection, and by radio-frequency (RF) heating are usually concentrated in the center of the plasma. The velocity distribution of these fast-ion populations is determined primarily by Coulomb scattering; during wave heating, perpendicular acceleration by the RF waves is also important. Transport of fast ions is typically much slower than thermal transport except during MHD events. Intense fast-ion populations drive collective instabilities. Implications for the behaviour of alphas in future devices are discussed.