This article discusses Amazon Elastic Load Balancing (ELB), a service that distributes incoming web traffic across Amazon EC2 instances in different availability zones. Monitoring ELB is crucial for maintaining smooth user experience and ensuring fault tolerance. Key performance metrics to monitor include RequestCount, SurgeQueueLength, SpilloverCount, HTTPCode_ELB_4XX, and HTTPCode_ELB_5XX. Additionally, backend-related metrics such as HealthyHostCount, UnHealthyHostCount, Latency, and BackendConnectionErrors should be monitored to gain a comprehensive understanding of ELB's performance and health. Monitoring these metrics helps identify potential issues and ensures optimal performance for web applications using ELB.