Annual recurring revenue (ARR)
The yearly value of all active subscriptions and recurring contracts, measured on one day. It's a snapshot of the subscription business rather than an accounting figure, so each company defines it a little differently.
Simple example
A software company has 100 customers, each paying $1,000 a month. Its monthly recurring revenue is $100,000, so its annual recurring revenue is $100,000 × 12 = $1.2 million.