Sure, I'll try and explain it better. This is the Windows version of Firefox. 
 
For example if I type "st" (without the quotation marks) in the URL bar it looks for all the previous URLs with "st" in them as well as home page or thread names. So it basically makes it a lot faster for me to find websites or threads I've read. So I don't have to type out a lot of the name of a website to have it pop up in my URL bar. It's sort of like an "intelligent" search feature in the URL bar. 
 
an example: 
 
 
Searching for "st" it brings up a thread with "West Germany" in it and "Acoustic Sounds" 
 
I can basically two or three letter search 90% of the websites I go to.