Bacteria has a simple cellular division process as compared to cellular division in higher multi cellular organism.
All bacteria's divide by the process of binary fission. Due to binary fission, a bacteria is able to reproduce every twenty minutes. in this way some bacteria's are able to produce millions of new bacteria is few hours only.
Hence, simple structure allows fast cellular division due to which bacteria can reproduce quickly.
Many reasons. Some bacteria are able to thrive under extreme conditions, have the ability to reproduce asexually, or have a variety of metabolic processes.
