Blue stragglers are thought to be formed from the merger or coalescence of
two stars, but the details of their formation in clusters has been difficult to
disentangle. We discuss the two main formation mechanisms for blue stragglers
(stellar collisions or mass transfer in a binary system). We then look at the
additional complications caused by the stars living in the dynamically active
environment of a star cluster. We review the recent observational and
theoretical work which addresses the question "which mechanism dominates?" and
conclude that the most likely answer is that both mechanisms are at work,
although with different importance in different environments and at different
times in the cluster lifetime. We finish with a short discussion of some
avenues for future workComment: 8 pages, 3 figures, to appear in the proceedings of the conference
"Binary Star Evolution: Mass Loss, Accretion, and Mergers" at Mykonos,
Greece, June 22-25, 201