I think it depends on what the time represents. When a user inputs a time, let's say for an alarm, this is always "wall clock", and this is what you store. The

I think it depends on what the time represents. When a user inputs a time, let's say for an alarm, this is always "wall clock", and this is what you store. The timezone can be stored too, but this is also dynamic. For example, a user put a conference in a calendar at 7 am, this is dependent of the user location the day of the conference. For app following the user, this is simple (like a mobile app), you just use the current timezone of the system the app is running on, but for a distributed system (client server), it might be complicated to pick a timezone and is dependent of the application. For computer times (like logging, cron...), just use UTC.