  In this paper we review recent results on symmetries in N=4 super Yang-Mills
theory. Symmetries are of invaluable help in studying and constraining the
scattering amplitudes, and there has been a lot of progress in recent years
concerning this topic. It has been realised that the ordinary superconformal
symmetry is not the full symmetry of this theory. There is indeed a dual
superconformal symmetry, and together they form a Yangian structure, pointing
to the underlying integrability of the theory. Here we give an overview of the
Yangian algebra and of its action on the scattering amplitudes, at tree and
loop level. This article is an invited review for the Focus Issue "Gauge/String
Duality 2011" of Advances in High Energy Physics.
