What's the difference between these connections?

What is the difference between DHCP, PPPoE, Static IP, PPTP, L2TP, TELSTRA? I'm trying to set up my wireless router but I don't know which connection to choose.

What is a VPN?

VPN is (Virtual Private Network) were first used by companies to enable their employees to securely access internal systems such as email remotely (e.g. from home or while on business trips). Today they are increasingly being used for personal use by individuals to protect their privacy while online in public places (e.g. when using the wi-fi connection in a cafe) or in a country where the internet is censored / blocked (e.g. China, Saudi Arabia��).