# - Definitions
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121 (one-to-one)
In Internet e-commerce, 121 is short for one-to-one, the philosophy that treating each customer as a special individual is a more successful approach than treating customers as a group of similar individuals.
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99.999 (Five nines or Five 9s)
In computers, 99.999 (often called "five 9s") refers to a desired percentage of availability of a given computer system.
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subscription management
Subscription management is the process of overseeing and controlling all aspects of products and services sold repeatedly through a weekly, monthly, quarterly or yearly subscription-based pricing model.