Seeing most of the living things on earth requires microscopes.
These things are so small that one can see through them rather well and at a level of detail that can inform us about the inner workings of all living things.
What makes a microscope an important tool in the study of living things?
I thought I'd expand a little on John's great answer! Microscopes really are an important tool in the study of living things.
- Making new antibiotics by being able to see and test which tiny bacteria are resistant to certain things
- IVF treatment - without microscopes we wouldn't be able to tell which sperm are slow or not
- Examining newly discovered life forms - as John said, most of the living things on Earth are so small that they need to be seen with a microscope, so with these we're able to find out about all the inner workings of the tiny creatures we share our home with!
I hope this has helped a little. You might find this video on the history of the microscope quite interesting: