Nine independent treatments that have been only lightly edited to retain the diverse styles and levels of formalization in the different areas of application. A unifying theme is that fractional derivatives arise as the infinitesimal generators of a class of translation- invariant convolution semigroups, which appear universally as attractors for coarse graining procedures or scale change, and are parametrized by a number in the unit interval corresponding to the order of the fractional derivative. After an introduction to fractional calculus, the topics include fractional time evolution, the fractional kinetics of Hamiltonian chaotic systems, and applications to problems in polymer physics and rheology.