The boundary conditions in today's plasma experiments and in later fusion plasmas are determined by the interactions of the plasma with the first solid wall. In today's experiments desorption by the plasma hitting the wall dominates, but ion backscattering, trapping and release, as well as sputtering of wall material, will dominate in machines with cleaner walls. The fluxes to the first wall for some of today's plasma experiments are reported and the data about the elementary processes at the first wall are shortly reviewed