Mitosis is basically the process of cell division. It is the mechanism by which the cell divides and forms two identical daughter cells. There are different stages of mitosis, with each stage signifying a special purpose and a special function. However, mitosis is part of the cell cycle, which are the different stages that a cell passes through in its life time.
The cell cycle consists of the G1, S, G2, Mitosis and Go phase. In G1 phase, the cell is capable of dividing but is currently going through the prerequisites. Normally the chromatin thicken and the nuclear membrane degrades at this stage. However, there is no DNA replication hence the daughter cells have the same number of chromosomes and DNA as their parent cells.