Essentially anywhere you want. You can check your email, browse the W orld W ide W eb or go read the newsgroups. It is up to you. URL stands for U niform R esource L ocator. Simply put, it is the address of a specific page on the World Wide Web.
POP is an acronym for P ost O ffice P rotocol.
It is the protocol used to retrieve email from a mail server. SMTP is a protocol for sending email messages. The most important thing to remember is that SMTP is the protocol used for sending email and POP is the protocol for receiving email. They work hand in hand. One of the things that you need to know is that software on the internet is distributed on the basis of an honor system.