Investing is parting with capital in the expectation of safety of principal and an adequate return on the capital in the form of dividends, interest or rent. Since the return on capital takes the form of periodic payments of interest or dividends, investing indicates an intention to be separated from the capital for an extended period of time. Therefore, investing is usually associated with relatively long time horizon. Buying stocks in a pension fund with the intention of holding them indefinitely, or buying bonds with the intention of holding until maturity, is investing.
Trading is basically an activity in which someone (usually called a dealer) makes a market in a given financial instrument. Traders try to extract the bid-ask spread from a market. An example of a trader is the specialist on the floor of a stock exchange. He matches orders, maintains an orderly market and is willing to buy at the bid and sell at the offer. Traders on the futures and options exchanges make two sided markets, trying to buy at the bid and sell at the offer. Traders in the over-the-counter stock and bond markets do the same thing. In its most basic definition, trading is market-making. The trader essentially tries to stay net flat (neither long nor short) and makes money by extracting the bid-ask spread. In this sense, Stu Gimble, my friend from the lumber and Eurodollar pits, was the consummate mechanical trader.
Speculating in its simplest form is buying for resale rather than for use or income as is the case for commodities or financial instruments, respectively. Speculating is parting with capital in the expectation of capital appreciation. This capital appreciation is the sole extent of "return" for the speculator. He does not anticipate return in the form of periodic dividends or interest payments, because he does not intend to hold the position for an extended period of time. The word speculation is derived from the Latin word specere which means to see. Speculating means vision, perception, the faculty of intellectual examination.
Betting is an agreement between two parties where the party proved wrong about the outcome of an uncertain event will forfeit a stipulated thing or sum to the other party. Therefore, a bet is about being right or wrong. For example, people bet on the result of an election or a football game. More often than not, they bet on whom they want to win rather than on whom they think will win. I always bet on Kentucky in basketball games. If I took into account the point spread, that would be speculating. If I had been a bookie taking bets either way, trying to keep my exposure even and extracting my commission, I would have been more like a trader who tries to stay net flat and extracts the bid-ask spread.
Gambling is a derivative of betting. To gamble is to wager money on the outcome of a game, contest or event, or to play a game of chance for money or other stakes. Gambling usually involves a game or event of chance; sometimes it involves games of both skill and chance. While gambling is popularly regarded as a vice that is injurious to public morals, it is actually a form of entertainment. Compulsive gambling might be injurious, but so is compulsive behavior of any kind. Gamblers may make money, but they are not deprived of enjoyment or entertainment if they do not make money. Individuals who lose a couple of hundred dollars in casinos are paying an entertainment fee, and they know it and have decided it's worth it. They engage in the activity for the action and the excitement of participation.
From _ What I learned losing a million.