High-availability clustering (also known as HA clustering or failover clustering) implies a group of servers that support server applications that can be reliably utilized with a minimum of downtime. Without clustering, if a server running a particular application crashes, the application will be unavailable until the crashed server is fixed. HA clustering remedies this situation by detecting hardware/software faults, and immediately restarting the application on another system without requiring administrative intervention, a process known as failover. HA clusters are often used for critical databases, file sharing on a network, business applications, customer services such as electronic commerce websites and all websites with a lot of regular visitors.

Load balancing is a computer networking method for distributing workloads across multiple computing resources that is crucial for high-load web projects enjoying large amounts of visitors and server requests. Load balancing aims to optimize resource use, maximize throughput, minimize response time, and avoid overload of any one of the resources. Using multiple components with load balancing instead of a single component may increase reliability through redundancy.