Why isn't all water salty?

Water in most of the world's oceans contain salt. Lakes, ponds and rivers that are created and sustained through rainfall and underground water sources are generally free of salt. When salt water evaporates (turns from a liquid to a gas), the gas escapes into the air but the salt stays in the surrounding water (e.g. the ocean). The gas that evaporated into the air eventually falls as rain (without any salt) into rivers, ponds and lakes.