by a ``modular form'' for a reductive group $g$ we mean an automorphic form that has some sort of very nice fourier expansion. the classic example are the holomorphic siegel modular forms, which are special automorphic functions for the group $\mathrm{sp}_{2g}$. following work of gan, gross, savin, and wallach, it turns out that there is a notion of modular forms on certain real forms of the exceptional groups. i will define these objects and explain what is known about them.