Churn Rate

Companies like Comcast and Netflix and Verizon have monthly subscribers to their service. When a subscriber leaves, they say that the sub "churned" off the service.

Why "churn"? Because the process is often circular, with the marginal subscribers leaving for a few months, attracted to some discount promotion by a competitor...only to return when the original service offers the same discount. The rate of this "firing of the service" is the churn rate.

Like...Verizon, in a given area, might have a million subs. About 10,000 per month fire Verizon, either because they've left to go to AT&T or Sprint, or have become Amish, or, uh...dead. That churn rate then is 1 percent a month.