Most altcoins are made by groups of pumps and landfills. What this means is that developers create a lot of hype for their coins and promise unique and interesting features. When people find out about these promises, they are more eager to buy coins at low prices, which in turn pushes prices up. Some altcoins have people who actively work hard outside pump-and-dump groups including Litecoin, CasinoCoin, and Guldencoin.