There are three main ideas of cell theory:

• All living organisms are made up or one or more cells.
• A cell is the basic unit of life
• All cells come from preexisting cells.

The cell theory is the basis of our understanding of cells. The theory evolved with the development of the microscope, observations of cells, and other related scientific discoveries. In simple terms, it states that cells are endowed with all the functionalities to survive as a living being. Cells are capable of combining with other cells, which has resulted in higher life forms such as human beings, plants and animals. The third tenet is important because it was earlier believed that cells can come out of nothing. We now know that cells can only come from preexisting cells, i.e. cells reproduce to generate new cells.