Freezeout vs. Rebuy/Add-On tournaments

Many tournaments are set up as “Freezeout”. This means, that you pay the buy-in at the beginning, receive a predetermined amount of chips, and when you lose them, you are out.
The second tournament type “Rebuy/Add-On” offers you options to buy more chips during the tournament if you are running low, and you wish to stay in the game. A Rebuy is usually set to the same buy-in and chip amount, and can be initiated only in the first or first few rounds of the tournament. An Add-On is the option to add on supplementary chips during the first or during first few pauses. It amounts sometimes up to 150% of the starting chips, usually again at the initial buy-in cost.