Bacteria reproduce very quickly because they don’t need other bacteria to help them like people do. Bacteria usually start eating soon after they’re born, and once they are large enough, they split in two creating two daughter cells. This is called asexual reproduction. This means that bacteria can reproduce exponentially. Exponential growth is so powerful that a single bacteria could produce hundreds of thousands of new bacteria in just six hours!
But bacteria can’t replicate forever. At some point they run out of food in their area, they are attacked by other cells, or they become trapped by other bacteria. That means they grow and grow, until they can’t grow any more. This is called the logarithmic curve.
You can experiment, growing your own bacteria in the simulation below. Press the green flag to start the simulation with a single bacteria. Then, make food by clicking on the white part of the simulation. As the bacteria eat the food they grow and divide. In the background, the purple line shows the growth of your bacteria. Is growth always exponential? Can't you keep going forever?