Domain flipping is a profitable online business where you buy domain names at a low cost and sell them at a higher price. It's similar to real estate flipping but focuses on digital real estate. To succeed, start by researching niches with high demand and low competition, then purchase valuable domain names through registrars like GoDaddy or Namecheap. Use platforms such as Sedo, Flippa, and GoDaddy Auctions to list and sell your domains. By understanding market trends, evaluating domain value, and effectively promoting your listings, you can earn substantial profits, with some domains selling for hundreds, thousands, or even millions of dollars.