  The ergm package supports the statistical analysis and simulation of network
data. It anchors the statnet suite of packages for network analysis in R
introduced in a special issue in Journal of Statistical Software in 2008. This
article provides an overview of the new functionality in the 2021 release of
ergm version 4. These include more flexible handling of nodal covariates, term
operators that extend and simplify model specification, new models for networks
with valued edges, improved handling of constraints on the sample space of
networks, and estimation with missing edge data. We also identify the new
packages in the statnet suite that extend ergm's functionality to other network
data types and structural features and the robust set of online resources that
support the statnet development process and applications.
