Elastic Load Balancers (ELB) in Amazon Web Services (AWS) automatically scale their capacity based on incoming application traffic. They are designed to handle traffic peaks and valleys without requiring manual intervention. The ELB adjusts its request processing capacity according to incoming traffic patterns and scales in response to the number of active connections or the rate of new connections, providing consistent performance. To help manage backend resources, combine ELB with AWS Auto Scaling groups. This way, you can automatically scale the number of EC2 instances based on demand, ensuring an efficient, balanced load across all available resources and high availability for your applications.