A load balancer is a device or software that distributes network traffic across multiple servers. This helps ensure that no single server becomes overwhelmed with too many requests, which can lead to slow performance or downtime. By balancing the load, it improves the overall efficiency and reliability of applications and services. Load balancers can operate at different layers of the network, such as the application layer or the transport layer. They can also provide additional features like health checks, which monitor the status of servers, and SSL termination, which helps secure data transmission. Common types of load balancers include hardware load balancers and software load balancers.