Excel Auto-Fill a Series Without Mouse (Keyboard Only)

Problem

When I want to extend a series or something along those lines, I can highlight a group of cells, then click on the bottom right corner of the highlighting box and drag down. Excel will then attempt to automatically extend the contents as well as it can. Is there a keyboard function that will allow me to do this? I like to use the keyboard to avoid repetitive mouse motions. I can use the shift key and arrow keys to make a selection, but I don't know what (if any) key can trigger this function. I also don't really know what this function is actually called.