The document reviews various energy-efficient routing algorithms aimed at maximizing the lifetime of wireless sensor networks (WSNs), which consist of battery-powered devices with limited energy reserves. It discusses algorithms that formulate routing as a linear programming problem, comparing their effectiveness in prolonging network lifetimes by balancing energy consumption across nodes. Additionally, the paper addresses specific algorithms and their advantages, limitations, and applications, emphasizing the trade-offs between using nodes fairly and extending their lifetimes.