A F5load balancer is a device that acts as a reverse proxy and distributes network or application traffic across multiple servers. Load balancers are used to increase capacity (concurrent users) and reliability of applications. They improve overall application performance by reducing the load on servers associated with managing and maintaining network sessions and applications, as well as performing application-specific tasks.

Load balancers are generally grouped into two categories: Layer 4 and Layer 7. Layer 4 load balancers act on data found in the transport and network layer protocols (IP, TCP, FTP, UDP) . Layer 7 load balancers distribute requests based on data found in application layer protocols, such as HTTP.

Requests are received by both types of load balancers and are distributed to a particular server based on a configured algorithm. Some industry standard algorithms are:

Round robin
Weighted round robin
Fewer connections
Shorter response time
what is a load balancer
Load Balancer Diagram
Layer 7 load balancers can distribute more requests based on application-specific data, such as HTTP headers, cookies, or data within the application message, such as the value of a specific parameter.

Load balancers ensure reliability and availability by monitoring the "health" of applications and only sending requests to servers and applications that can respond in a timely manner.