Is it true that the organisms that can only be seen under a microscope are called microorganisms?

Organisms that can only be seen under a microscope are referred to as microorganisms or microbes. This includes bacteria, viruses, fungi, and protists. These organisms are too small to be seen with the naked eye, and their size is typically measured in micrometers (µm) or nanometers (nm). Despite their small size, microorganisms play a critical role in many aspects of life on Earth, including nutrient cycling, food production, and human health.