Water hard or soft

Life or something like it what in the world is going on and what is th eworst thing that you think can happen when things go on in this world, i have a friend that puts a filter on her bath water just so that she can have soft and not hard water on her skill. i'm thinking i will just recommend her to have a distributor water filter so that she can have soft water all in her house

i'm sorry what is hard water