Everybody knows that sea water is salty. This means that some salt in the dissolved form is present in sea water. One gallon of sea water contains about one hundred grams of salt. In general sea water has 4% to 6% salt in it. In comparison to open seas, the quantity of salt in closed seas like the Mediterranean and the Red Sea is more. If salt of all the oceans is collected and dried, one can make a 288 km high and 1.6 km thick wall with this salt, which will be long enough to encircle the entire perimeter of the Earth along the equator.
Do you know from where this salt comes in the sea water? We know that salt is soluble in water. Rain 
water carries salt and other minerals present in the Earth’s crust to the rivers (which make river water salty) which, in turn, take them to the ocean. The water of the oceans evaporates to the atmosphere and again falls on to the Earth in the form of rain, but the salt is left in the oceans because salt cannot be evaporated. This cycle has been continuing for millions of years and as a result the salt content of the oceans has been increasing continuously. This explains the presence of large quantities of salt in sea water.
The common salt used every day by us in our kitchens is produced from the sea water or from the water of saline lakes.