What are the benefits of a unicellular lifestyle?

Many living organisms are unicellular. These are whole kingdoms of the living, such as protists, archaea or bacteria. They have some advantages, which is why they exist together with unicellular organisms, and some species have been on our planet for millions of years. The advantages are that the unicellular type of structure is very simple. They do not need complex systems to carry out various processes. Also, they multiply very quickly, since cell division does not require much energy and proceeds relatively very quickly.