What occurs during the S-phase of the cell cycle?

[RamonitaBe]

I'm studying the stages of the cell cycle and want to know what happens in the S-phase. Can someone explain its main function and importance?

 

[DeeReich70]

During the S-phase (Synthesis phase) of the cell cycle, the cell replicates its DNA, creating an identical copy of each chromosome. This ensures that when the cell later divides during mitosis or meiosis, each daughter cell receives a complete set of genetic information.