In this talk I will discuss infinite-type surfaces (e.g. surfaces of
infinite genus). I will show how infinite-type surfaces can be seen as
subsurfaces of themselves in a nontrivial way, how to use this fact to
select a class of arcs on a surface and to construct a graph with an
interesting action by the group of symmetries of the surface (the
so-called mapping class group). Joint work with Tyrone Ghaswala and Alan
McLeay.