We can use the Lean Startup mindset whether we're setting out to build a new product or creating a new feature for an existing one. The core concepts remain the same; first put together the hypothesis, and next create a release strategy which focuses the first release on the minimum core feature set that we need to validate our idea with.
We then build it and test it out with a user group that will give us constructive feedback. This group is often known as our "early adopter" group because they love using new technology, and if it solves a problem that they care about they won't be too concerned about the little "problems" an early product might have.
In the next section we give an example of a real-world MVP and how we can use the build-measure-learn cycle to validate an idea as quickly as possible. It illustrates how we can use the principle even on existing products.