What are microorganisms?

Explanation

### Step-by-Step Solution:

1. **Definition of Microorganisms**: Microorganisms are tiny living organisms that are usually too small to be seen with the naked eye. They can only be observed using a microscope.

2. **Size and Visibility**: The term "micro" in microorganisms indicates their small size. Because of their minuscule dimensions, they require special tools (like microscopes) for observation.

3. **Types of Microorganisms**: There are various types of microorganisms, including:
- **Bacteria**: Single-celled organisms that can be beneficial or harmful.
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