Active user counts are most useful viewed over time to get insights into growth, engagement, and user retention.
A/A testing involves running an A/B testing process with two identical versions in order to ensure the testing process is in working order.
A/B/n testing is the process of A/B testing with more than two different versions. The “n” is not a third test, it refers to any additional tests.
A/B testing can be very similar, with only a change in button color, or very different, with a total change in the way a feature behaves.