Arrrrgggghhh!!! What is a trackback?!?!?!?!

Hi, I have a problem, can you lend me a helping hand? For some time now, I have been trying to understand what a "trackback" is!? But I just don't get what it is all about! I looked up the meaning of "trackback" in the internet, but I still don't know what it is all about!

Here is the definition provided by www.haloscan.com:

Trackback is a system that alerts and allows a blogger to see who blogged about posts in his/her blog. The system works by sending a ping between the blogs, and therefore sending an alert.

Say what!? Ano daw (tagalog of say what)!? Can someone explain to me in plain english or tagalog??? Please helllllllppppppppp!!!?!!!