A load balancer is a piece of hardware (or virtual hardware) that acts like a reverse proxy to distribute network and/or application traffic across different servers. A load balancer is used to improve the concurrent user capacity and overall reliability of applications. A load balancer helps to improve these by distributing the workload across multiple servers, decreasing the overall burden placed on each server.
Physical load balancing appliances are similar in appearance to routers. They are connected to your network infrastructure in the same manner as a router or another server.