Do you have any ideas about differences Among the Light Sockets?

This article is telling about the different sockets names and basis, sizes. For example LED Replacement Bulb.You may use the light, but you don't know much about the details, I found it from wikiHow website, as below is the address, for your interesting,you can take have a look.
http://www.wikihow.com/Tell-the-Differences-Among-the-Light-Sockets