The first-use flow that takes a new user from signup to actual value, built to maximize how many make it across that gap before bouncing.
Duolingo flipped the standard signup order: pick a language, set a daily goal, take a placement quiz, then create an account. By the time the email field appears, the user has already taken a lesson, which lifted activation enough that the inverted flow is now copied across consumer apps. Duolingo went public in 2021 partly on the strength of those activation numbers.