At John F. Kennedy International Airport (JFK), you generally cannot walk between terminals after passing through security, as most terminals are physically separate buildings that are not connected airside. Each terminal (1, 4, 5, 7, and 8) has its own independent security checkpoints. If you need to transfer from one terminal to another—for example, arriving on an international flight in Terminal 4 and connecting to a JetBlue flight in Terminal 5—you must exit the secure area, take the AirTrain (which is free for inter-terminal travel), and then re-clear TSA security at your new terminal. There is one minor exception: Terminal 4 is massive and has some internal walking routes between its own concourses, but moving between different numbered terminals almost always requires "landside" transit. One notable airside connection exists between Terminal 5 and the TWA Hotel, but this is for lodging, not for catching flights in other terminals. Delta also occasionally operates airside shuttle buses for specific connections within their own network, but for the average traveler, the rule of thumb at JFK is: "New terminal, new security line."