What is mean by microorganisms
Living organisms which are not visible to the naked eye are known as micro-organisms. They are the tiniest possible living organisms that are too small to be seen through naked eyes. They are living organisms that can be seen only with a microscope or a magnifying glass.
Microorganisms were observed for the first time by Anton von Leeuwenhoek in 1674, using a microscope of his own.
Microorganisms make up the largest number of living organisms on the planet. They are not just billions or trillions around the earth, but trillions of trillions and many more. There is a huge variety of microorganisms present on earth.
Microorganisms can be classified into four major groups depending on their characteristics- Bacteria, fungi, protozoa and algae.
Viruses are also types of microorganisms, but they cannot reproduce on their own and require a host cell to complete their life cycle. They are non-living outside the host but living when present inside the host.