The period of life cycle of cell (cell cycle) between two consecutive divisions is termed as the Interphase or misleading called resting phase.
It is a period of great metabolic activity that typically occupies 90% of the total cell cycle. It is the period during which the normal activities of the cell take place.Inter phase also sets the stage for the cell division because DNA replication is completed during the S phase of the inter phase. Before a cell divides, the DNA in its nucleus must produce an exact copy of itself. This process is called replication because the double stranded DNA makes a replica, or duplicate, of itself. Replication is essential to ensure that each daughter cell receives the same genetic material as is present in the parent cell.

Replication begins with the strands of DNA untwisting .A DNA helicase enzyme breaks the weak hydrogen bonds joining the purine and pyrimidine bases, and the DNA molecules begins to itself.As soon as new bonds forms, the untwisted strands begin to twist again.