What is meant by crystallisation? How is impure copper sulphate purified by the process?

(N/A) Crystallisation is a process that separates a pure solid in the form of its crystals from a solution.
$AIM$: To obtain crystals of pure copper sulphate from an impure sample.
Procedure:
$(i)$ Take some impure sample of copper sulphate in a china dish (approximately $5 \ g$).
$(ii)$ Dissolve the contents in a minimum amount of water and filter the impurities out.
$(iii)$ Evaporate water from the solution to get a saturated solution of copper sulphate.
$(iv)$ Cover the solution with a filter paper and leave it undisturbed at room temperature to cool slowly for a day.
Observation: The crystals of copper sulphate can be seen in the china dish.
Conclusion: The process of formation of crystals of a pure solid from a solution is called crystallisation.