It is really hard to know where to start on this question because the microscope has had such a huge impact on biology and on science in general.
I suppose the most profound impact of the microscope came when Anton van Leeuwenhoek discovered microbes in the 1670s using a microscope that he had designed.
Up until that point, people had no idea that there was a whole world of microorganisms too small to be seen by the naked eye. With this discovery, it became possible to start learning about, among other things, the causes of diseases.
I am sure that there are tons of ways the microscope has helped the development of biology in particular and science in general. However, I would say that the most important impact is that the microscope has opened the eyes of people to a whole new world of organisms that were once invisible to the human eye. Moreover, by looking at these organisms, biology and science is able to learn more about the world and how it works. Also on a more practical level, science can make better medicines and other things to help humanity.
In a family of Holland, microscope was created in 1590. Zaccharias Janssen and his father Hans, have found that if they put two such lenses in a cylinder, they could see very small things that would increase even more than 10 times. Compared to the magnifying glass before, which used a single lens, they were using now two or more lenses, which essentially were creating a compound microscope.
Meanwhile, on the same principle,spyglass was created, based on two lenses placed in a cylinder. But the spyglass could look away. Spyglass was very useful at sea, in search of land, or on the battlefield, to spy on enemy movements remotely. This news about spyglass invention came in the summer of 1609 to the ears of Galileo Galilei, who was on holiday, in Venice. In one night, Galileo Galilei was able to build his own telescope, which was increasing the image about 30 times. He perfected it in a few weeks and the increasing developed to 300 times.
Robert Hooke was the first man who used increasing new tools, to look in detail to the small universe. Hooke focused on living organisms, whom details were too small to be seen with the naked eye. Hooke looked carefully insects, worms, plants and so on.
And as always when a new scientific tool appears which allows the study of something that had never studied, the surprises of nature appear as discoveries. These discoveries have been presented in his book Micrographia, which he published in 1665, with detailed description of his comments, book that is the first book in the world to popularize science, speaking to ordinary people without scientific training.There was no need to be a scientist to enjoy those files, that mankind first saw them.
The most important finding is the existence of cells in living organisms . Robert Hooke made the discover about living cells and gave the name of cell, because cells reminded him of the cells in a convent or prison.
Second, the microscope has allowed the first study in detail of the difference between living shells and fossilized shells, and between wood and petrified wood. This allowed Hooke to be the first man to deliver the assumption (which proved correct) about the process of fossilization, the replacement of living tissue with minerals, but also keeping the shape of the alive original.
After the invention of the microscope , the knowledge of biology had become extensive. Inside biology began to form many branches with well-defined areas of study. Some of these branches are of mainly theoretical character as botany, zoology, taxonomy and other have predominantly a practical nature, such as agriculture and horticulture.
Microscope refers to a very broad class of instrument that facilitate visual study of small objects by magnifying their image visible to the eye. The microscopes come in a very wide range in terms of their design and the extent of magnification achieved.
Microscope have been very useful in all fields of human activities including scientific investigation that require visual examination of very small objects or minute details of bigger objects. The microscope has been particularly useful in the area of biology as it has facilitates study of very minute objects such as cells of organisms and the components of these cells.
The use of microscope led to many great discoveries in biology during seventeenth century. Micrographia, a book published in 1665, presented drawings of many biological specimens including as seen through microscope. The microscopic life form was first discovered in 1670 by Anton Van Leeuwenhoeck using microscope, which opened a whole new field of investigation in biology.
In Holland Zacharias Jansenn was in the business of grinding lenses for eyeglasses . Some of his lenses made things look bigger. He found that he could put two lenses together to make things look a lot bigger. Zacharias built the first microscope in 1595. The first microscopes made things look 20 or 30 times larger than they are.
In the 1600's, another man Anton van Leeuwenhoek who lived in Holland, began to make microscopes as a hobby. He was in the business of selling cloth, but he became very good at making microscopes. His microscopes could magnify an object up to 200 times.