First, remember there is only one difference between known and anonymous user profiles: known user profiles have a Login ID (a user identity that can be used to identify one, and only one, user profile), while anonymous user profiles do not have a Login ID.
Regardless of the identity strategy configured for your account, as soon as a user begins interacting with your app or website, a new anonymous user profile is created to store the user’s data. How you convert that user from an anonymous to known varies depending on the identity strategy you have configured for your mParticle account.
If you are using either the Profile Link or Profile Conversion strategies, then as soon as a new Login ID (one that is not associated with any existing profiles) is supplied to mParticle (either through an automatic identify call or a login call triggered by your app, then a new known profile is created to store data for the user.
Now that the user is known, you may use aliasing to copy over any data that was gathered when the user was anonymous. Aliasing helps to maintain a complete picture of your users throughout their journey through your marketing funnel.
The best match identity strategy does not support known user profiles. If you are using this strategy, then whenever your app triggers an identify request, mParticle will return the user profile that most closely matches the provided identities according to your identity priority. There is no transition from anonymous to known.
The profile isolation strategy will create a new known user profile as soon as a new Login ID is detected. This will transition the user from anonymous to known, but no data collected from when the user was anonymous will be transferred to the new profile.