  We develop in detail most of the theory of the Picard scheme that
Grothendieck sketched in two Bourbaki talks and in commentaries on them. Also,
we review in brief much of the rest of the theory developed by Grothendieck and
by others. But we begin with a twelve-page historical introduction, which
traces the development of the ideas from Bernoulli to Grothendieck, and which
may appeal to a wider audience.
