What is mean by Water cement ratio? why it is needed?

Question

Kindly give me a detailed answer..

Answer 1

Water-cement ratio is the ratio of weight of water to the weight of cement used in a concrete mix. It has an important influence on the quality of concrete produced. A lower water-cement ratio leads to higher strength and durability, but may make the mix more difficult to place. Placement difficulties can be resolved by using plasticizer. The water-cement ratio is independent of the total cement content (and the total water content) of a concrete mix.

Answer 2

the ratio of water added to the amount of cement added in an aggregate constitute the water cement ratio......

the amount of water added is important to excel the reaction in cement so as the gypsum takes its time to set