How does Ethereum MEV work?

Could you please elaborate on the workings of Ethereum's Maximal Extractable Value (MEV)? How does it come into play in the blockchain ecosystem, and what are the implications for users and developers? Is it a positive or negative force in the Ethereum network, and how does it affect transaction fees and miner incentives? Understanding the intricacies of MEV is crucial for anyone navigating the complex landscape of decentralized finance.