  We provide a lightning review of the construction of (generalised) orbifolds
[arXiv:0909.5013, arXiv:1210.6363] of two-dimensional quantum field theories in
terms of topological defects, along the lines of [arXiv:1307.3141]. This
universal perspective has many applications, some of which we sketch in the
examples of 2d Yang-Mills theory, Landau-Ginzburg models, and rational CFT.
