What does marine desalination mean?

Desalination is the process of removing the salt fraction from salt water, generally from sea water, to obtain water with a lower salt content.
Brackish and sea waters are subjected to desalination to make them suitable for drinking or industrial uses, a particularly useful operation for arid or semi-arid areas and for several islands without adequate water refilling.

Even for regions where water supply is sufficient, desalination, if carried out under economically competitive conditions with other types of supply, can represent a reassuring coverage in view of future expansions and a suitable means to face water demand peaks concentrated in time, for example in places of tourist interest in the summer period.