Split horizon with poison reverse

I am currently sudying for the CCNA. I have come across the terms route poisoning and split horizon with poison reverse. I have read the cisco explanation and several online definitions and it is still not very clear. Does anybody here know what this is and how it works? If anybody can make this clear I will be grateful.

 

Old thread, but in case anyone out there is wondering:

Split horizon allows a router to prevent loops by not advertising a learned route back out to the interface from which it was learned.

Poison reverse takes loop prevention a step further, by advertising routes as unreachable over the interface from which they were learned by setting the route metric to 16 (as you recall, 16 would be the 17th hop, so it's considered unreachable at that metric).

 

Dont bring back 5 or more year old threads.