Having better service capacity with high availability and low latency is mission critical for almost all businesses.
Availability MEANS the ability of the application user to access the system, If a user cannot access the application, it is assumed unavailable. High Availability means the application will be AVAILABLE, WITHOUTINTERRUPTION.
Achieving high availability for a application is not always a easy TASK. Using redundant server nodes with clustering is a common way to achieve higher level of availability in web applications.
Availability is commonly expressed as a percentage of uptime in a given year.