What is a guaranteed poker tournament?

A. Guaranteed poker tournaments usually have a guaranteed prize pool, for example $2000 guaranteed. Some rooms make add-ons applicable, so there is a possibility to buy chips (unlimited buy before 1st break; one buy during 2nd break no matter how many chips the player has). The money for add-ons goes to the prize pool, so if there are more buy-ins than guaranteed prize pool, the total money pool increases according to the add-ons amount. This is very good, because winners recieve more than stated before the tournament starts.