What happens when water is added to an anhydrous salt?

When water is added to an anhydrous salt, the hydrated salt is formed. The hydrated salt takes the  form of a solid compound which has water in the form of H2O molecules associated with it. For example, anhydrous copper sulfate is a white solid with the formula CuSO4. When crystallized from water, a blue crystalline solid which contains water molecules as part of the crystals is formed. Analysis shows that the water is present in a definite amount, and the hydrate may be given the formula CuSO4 · 5H2O. This associated water of crystallisation forms part of the crystal lat ice of the hydrated salt - note that the anhydrous salt does not form crystals and is an amorphous powder.Water is present in definite proportions in the crystal structure without being associated directly with the anion or cation. The water occupies a definite place in the crystal lattice.