  The minimum rank problem for a (simple) graph $G$ is to determine the
smallest possible rank over all real symmetric matrices whose $ij$th entry (for
$i\neq j$) is nonzero whenever $\{i,j\}$ is an edge in $G$ and is zero
otherwise. This paper surveys the many developments on the (standard) minimum
rank problem and its variants since the survey paper \cite{FH}. In particular,
positive semidefinite minimum rank, zero forcing parameters, and minimum rank
problems for patterns are discussed.
