The Source engine is a 3D video game engine developed by Valve. The Source engine is well-known for its advancements in physics, AI, and graphics which made the games realistic for its time, while being scalable on older, less powerful hardware. Source engine servers are hosted game services that allow players to connect and play together in the server's world. Servers in the Source engine can be customized with mods that results in a unique and often times fun gameplay experience for all players connected to the server.
This is a companion discussion topic for the original entry at https://blog.moddingcommunity.com/hardware-network-requirements-for-source-engine-servers