JIT arbitrage occurs when a searcher sees a large swap in the mempool and then sandwiches the trade with liquidity in the underlying pool. MEV searchers and DeFi protocol developers frequently use this term. To excel in JIT arbitrage, one should have a deep understanding of DeFi protocols (especially AMMs), be proficient in mempool monitoring and high-speed transaction submission, and understand the intricacies of liquidity provision and removal in DeFi pools.