In my own understanding, Altcoin is an alternative digital currency of bitcoin or simply called bitcoin clone. I think it's been created because bitcoin is too expensive to buy it directly so most of the people are don't have a capacity to avail bitcoin. But because of altcoin many of the community had a chance to buy on cheap price which can be multiply by more than we invest it can be triple or quadruplet the value of the coins. which once its being sold it will directly send it to the bitcoin balance.