Having better service capacity with high availability and low latency is mission critical for almost all businesses.
Availability means the ability of the application used to access the system, If a user cannot access the application, it is assumed unavailable. High Availability means the application will be available, without interruption.
Achieving high availability for an application is not always an easy task. Using redundant server nodes with clustering is a common way to achieve a higher level of availability in web applications.
Availability is commonly expressed as a percentage of uptime in a given year.