A cell is the basic unit of living organisms that is capable of reproducing itself exactly. That is, although eukaryotic cells (such as plant cells and animal cells) contain components, which are called organelles, those components do not reproduce themselves independently of the cell of which they are a part.
A centrosome, which is sometimes referred to as a "centrosphere", is an area or region of clear cytoplasm located next to the nucleus in non-dividing cells.
Centrosomes contain centrioles - which are responsible for cell-division.
See also the functions of cell organelles.