Differential algebraic function field of one variable.- Movable singularities.- Fuchs' theorem.- Extensions of the coefficient field.- Briot-Bouquet's theorem.- Clairaut fields.- Poincaré fields.- Analogs of addition formulae for elliptic functions.- Poincaré fields generated by the constants.- Poincaré fields of characteristic 0.- Automorphisms of an elliptic field.- Differential automorphisms.- Differential automorphisms of a Poincaré field.- Riccati fields of characteristic 0.- Weierstrass points.- Clairaut fields of characteristic 0.- Movable singularities in case of characteristic 0.- Differential Lefschetz principle.