nLab automorphism of free group

It appears that the group $Aut(F_n)$ of automorphisms of the free group $F_n$ on $n$ letters and especially the group $Out(F_n)$ of outer automorphisms of the free group on $n$ letters appear often at sometimes unexpected places in geometry, theory of operads, deformation theory, study of moduli spaces etc. Some of the occurences are expressed in terms of Kontsevich’s graph homology, ribbon diagrams and alike.

Some of the authors who wrote extensively on related issues include Karen Vogtmann (homepage). Cf. also articles by Leila Schneps etc.