Modern arcade machines, far from being isolated islands of entertainment, are often complex computer systems connected to networks. This connectivity enables crucial features like online multiplayer gameplay, global leaderboards, remote diagnostics, and content updates. The networking protocols facilitating these functions are largely inherited from the broader PC and internet technology world.

The most common networking protocols found in arcade machines are:

1. TCP/IP (Transmission Control Protocol/Internet Protocol): This is the fundamental suite of protocols that forms the backbone of the modern internet and most local area networks (LANs). Virtually every networked arcade machine utilizes TCP/IP for communication. TCP is used for tasks that require reliable, ordered data delivery, such as downloading a new game patch or syncing high-score data to a central server where every packet must arrive correctly.

2. UDP (User Datagram Protocol): Also operating on top of IP, UDP is favored for real-time, speed-critical applications. Its connectionless and lightweight nature (lacking error-checking and retransmission features) makes it ideal for online multiplayer gameplay in fighting games or racers. A few dropped packets are preferable to the lag introduced by waiting for TCP to retransmit them, ensuring smoother real-time action.

3. HTTP/HTTPS (Hypertext Transfer Protocol/Secure): This application-layer protocol runs on top of TCP. Arcade machines use HTTP/S to communicate with web services. This is most commonly seen when:

* Posting scores to online leaderboards.

* Downloading new game content or updates from a manufacturer's server.

* Processing in-game purchases or validating tokens.

4. NetBIOS (Network Basic Input/Output System): While older, this protocol is still frequently encountered in arcade environments, especially for local network communication within an arcade or on a specific LAN. It helps machines easily discover and communicate with each other for casual LAN multiplayer matches or to locate a central server for score aggregation.

5. SMB (Server Message Block): This protocol is used for providing shared access to files, printers, and serial ports on a network. In an arcade context, a central server might use SMB to distribute new game ROMs or configuration files to a bank of cabinets on the local network, making management efficient for operators.

In summary, while the games themselves provide the fun, it is this blend of reliable (TCP) and fast (UDP) protocols, supported by application standards like HTTPS and network services like NetBIOS/SMB, that power the connected arcade experience, from a competitive online match to a simple high-score upload.