If you are into crypto trading, you could have come across occasion when opportunities to buy coins at lower price in one exchanger and sell at higher price in another exchanger. For instance, USDT could be bought at cheap price in coinbase and sell at high price in Binance. This opportunity don't last more just few months before it is closed. When arbitrage opportunity arises, thousands of income could be made. One thing I like about this arbitrage is that as one opportunity of arbitrage in one coin closed, another one of other coins opened. Your chances of discovering arbitrage opportunity depends on how resourceful you are.