Microorganisms cannot be seen with the naked eye because they are very small. They can be seen with the help of a microscope. It is an instrument that produces enlarged images of small objects, thus
allowing the observer to see an exceedingly close view of minute structures at a scale convenient for examination and analysis.
A simple microscope consists of a single lens that magnifies the object. A compound microscope consists of two lens system and is used for better magnification. The magnifying power of a microscope is an expression of the number of times, the object being examined appears to be enlarged.