What counts as a 'train' on trains.fyi?

If a layperson would call it a train, it qualifies. That includes:

• Heavy rail — intercity, commuter, and regional trains (Amtrak, VIA, GO Transit, MBTA, etc.)
• Metro / subway — fully grade-separated urban rail
• Light rail — including LRT and tram-train hybrids
• Streetcars / trams — even when they share the road with cars
• People movers and monorails at airports and theme parks where data exists

We don't include buses, ferries, or cable cars, even when they appear in the same GTFS feed as a city's trains.