Yes, all four passenger terminals at Singapore Changi Airport are connected, but the method of connection varies. Terminals 1, 2, and 3 are directly linked both "landside" (public area) and "airside" (transit area) via a free, high-speed Skytrain and pedestrian bridges. These three terminals also encircle Jewel Changi, a massive retail and nature complex that serves as a central hub. Terminal 4, however, is geographically separate. It is connected to the other three terminals via a complimentary 24/7 shuttle bus service that runs every few minutes. The bus ride between T4 and the other terminals takes about 10–15 minutes. If you are a transit passenger, you can move between all four terminals without clearing immigration, provided you follow the "Transit" signs and use the airside shuttle buses or Skytrains. This interconnectedness allows you to enjoy gardens and lounges across the entire airport regardless of which terminal you depart from.