What is Load Balancer? Load balancer is a virtual or physical device which distributes network traffic to clustered servers. It improves responsiveness and increases availability of applications. Load balancer is an interface between client and server which acts as an advisor for the client network and request traffic. Passes the requests to the right server by using various load balancing algorithms. Which reduces the load on single server and prevents any one application server from becoming a single point of failure. It results applications availability and response time.