The cell is smallest unit of life .Cells may be compared with bricks and can be called building blocks of the body of the living organism.Organisms can be classified as unicellular (consisting of a single cell; including most bacteria) or multicellular (including plants and animals). Humans contain about 10 trillion (1013) cells. Organism differ from one another , however cells are common to all. There are millions of living organism.
Human body has trillions of cells which vary in shapes and sizes. The organism made of more than one cell are called multicellular organism .
Here is 10 Questions on Cell