the notion of biexactness for groups was introduced by ozawa in 2004 and has since become a major tool used for studying solidity of von neumann algebras. we introduce the notion of biexactness for von neumann algebras, which allows us to place many previous solidity results in a more systematic context, and naturally leads to extensions of these results. we will also discuss examples of solid factors that are not biexact. this is a joint work with jesse peterson.