  This year marks the hundredth anniversary of Einstein's 1915 landmark paper
"Die Feldgleichungen der Gravitation" in which the field equations of general
relativity were correctly formulated for the first time, thus rendering general
relativity a complete theory. Over the subsequent hundred years physicists and
astronomers have struggled with uncovering the consequences and applications of
these equations. This contribution, which was written as an introduction to six
chapters dealing with the connection between general relativity and cosmology
that will appear in the two-volume book "One Hundred Years of General
Relativity: From Genesis and Empirical Foundations to Gravitational Waves,
Cosmology and Quantum Gravity," endeavors to provide a historical overview of
the connection between general relativity and cosmology, two areas whose
development has been closely intertwined.
