Here, I will be guiding you on how to setup your GMail account on your Android phone for POP3 and IMAP access. I have to say, this process can be a lot more complex if you are setting up POP3 on other device, but Android has made it very easy for GMail.
First of all, if you do not know what a POP3 is, here is a brief introduction. Basically, POP3 stands for (Post Office Protocol 3) which is currently the most common e-mail server/client protocol. Your e-mails are held by the server, and your client accesses it at intervals in order to synchronize the e-mails on the server. In older days, e-mails were deleted immediately from the server the moment it was downloaded to the client, but with some programming on the mailserver, the emails can be retained on the server. Thanks to GMail, they give us several options to choose from for the purpose.
Without wasting time, here is EVERYTHING you will need to do in order to get your E-Mail running as POP3 on your Android.
What you need: A GMail account & An Android phone (Nexus One/Garmin-Asus A10/Garmin-Asus A50 tested for this tutorial).
Hope that helps