Pink Himalayan salt is a form of rock salt that is sourced from the Punjab region in Pakistan near the Himalaya mountains. While this salt is 98% sodium chloride (compared to normal table salt) it does contain certain trace minerals including magnesium, calcium and potassium which are responsible for its coloration.
People use this it in the same way that they would normal salt: for cooking, to season meals and to prepare food. Some people believe that it has additional health benefits because it has a slightly lower level of sodium content and because of the trace elements it contains. It is also regarded as a more natural salt because it has not been refined like table salt (which also contains ant-caking agents), contains no additives and is composed of larger crystals than table salt (meaning less can be used to achieve the same taste).