When browsing sites the links can be set to open new windows.
For example:
But some site owners prefer to open the link in the same window.
This can be annoying if you want to keep the current page active. You end up having to hit the back arrow a number of times if you get deep into another site via the link.
Simple solution is to hold down the 'Ctrl' as you click the link.This will force a new window for the link no matter what the link itself defines.