This post contains many high yield images that help to identify some of the identifying features of the ileum, the third portion of the small intestines. If you haven't already, be sure to read A Histology Tour of the GI Tract- Small Intestines Overview before continuing...
Functions of the Ileum
Villi have absorptive function
Microvilli increase the surface area of absorption
Muscularis externa helps in churning food particles i.e peristalsis