Diverse results concerning Besov and Sobolev spaces

A survey of some author's results covering four decades (1974 – 2014) will be presented including: approaching a constant for functions with finite Besov semi-norm, spaces of functions of generalized smoothness (various descriptions, trace problem, restrictions on Lipschitz domain, capacity estimates); sharp constants in the Kolmogorov, Friedrichs, Poincare and Wirtinger inequalities for Sobolev spaces on the half-line and on the finite segments.