This is a short expository paper on blenders for people with any mathematical background. These objects, which are in some sense fat horseshoes, were introduced by C. Bonatti and L. J. Díaz [Ann. of Math. (2) 143 (1996), no. 2, 357–396], who used them to construct new examples of robustly transitive diffeomorphisms. These objects were already implicitly present in the study of heterodimensional cycles and bifurcations of dynamical systems. Recently they started to appear with many other applications, such as stable ergodicity, fractal geometry and algebraic dynamics, etc. The paper is short and very well written so it makes more sense to invite the reader to read the paper than to expand the review further.