An edge is something that someone has that gives them an advantage over another party. This advantage cannot be learned or its value would be diluted. An edge is usually very expensive to acquire. There are large barriers to entry. For example, option market makers use to have a huge edge. But they PAID for it through their seat memberships. LTCM had an edge. They provided liquidity for the world debt markets. So they earned a spread for providing liquidity. They got to borrow money at virtually no cost as well. Citadel has an edge via their ability to own order flow and execute trades with zero slippage, and in many cases at a discount or premium to the marketplace. Floor traders at the CME and CBOT use to have an edge by trading in front of order flow. They PAID for this through their memberships. Some hedge funds in the past were able to get news before other people could and trade off of it. They were able to get order flow info by calling around. That was an edge. Some futures traders are able to execute their orders faster than other traders by getting priority in the queue ahead of other people. They paid for this through technology cost. Arbitrage is a legitimate edge usually vis-a-vis providing liquidity. Other edges existed in tax laws, information flows, PIPES, convertible bonds arbs, etc. These are all legitimate edges. They all came out at a cost. Very few people could execute these edges. They were not learned, they were created or acquired. Being able to buy XYZ when it breaks through a moving average is not an edge. Selling something after a gravestone doji is formed is not an edge. Buying a market that is oversold on some oscillator is not an edge. Market profile is not an edge. Neither are using support or resistance levels. Neither is fundamental analysis.