From the introduction:
igraph is a free software package for creating and manipulating undirected and directed graphs. It includes implementations for classic graph theory problems like minimum spanning trees and network flow, and also implements algorithms for some recent network analysis methods, like community structure search.
The efficient implementation of igraph allows it to handle graphs with millions of vertices and edges. The rule of thumb is that if your graph fits into the physical memory then igraph can handle it.
OK, I’m packing n x GB of RAM, so should be able to do some serious damage.
There are too many changes, features and fixes to easily summarize them. See Release Notes 0.6.
Documentation for igraph is available for R, C and Python interfaces. Features are not always the same across interfaces.
I mention that because in this release, in the R interface, vertexes and edges are numbered from one. For C and Python, vertexes and edges continue to be counted from zero.