What are the three principles of cell theory?

The three principles of cell theory are:

All living organisms are composed of one or more cells: This principle states that all living things, whether they are simple single-celled organisms or complex multicellular organisms, are made up of cells.
The cell is the basic unit of structure and organization in organisms: This principle emphasizes that the cell is the fundamental building block of life. All the structures and functions of an organism are ultimately carried out by cells.
All cells come from pre-existing cells: This principle proposes that cells arise only from pre-existing cells through cell division. This concept refutes the previously held idea of spontaneous generation and supports the idea of continuity of life through the reproduction of cells.