The $100^{\mathrm{th}}$ Anniversary of the Birthday of Sergei L'vovich Sobolev

An essay on the life and work of Sergei L'vovich Sobolev (1908–1989), an outstanding mathematician of the $20^{\mathrm{th}}$ century, is presented. His works laid the foundations for intensive developments of the modern theory of partial differential equations and equations of mathematical physics, and they were a gold mine for new directions of functional analysis and computational mathematics.