What should a developer of multiplayer online games need to know?

Question

Game development

What should be studied first? What topics in terms of computer networks you need to know without going into details.
PS I work with the SFML library, where there is a module / interface for interacting with the network.

Answer 1

1. API for asynchronous processing of events from different sockets (kqueue, epoll, select)
2. Data structures - they are more important than algorithms.
3. Space-time issues) when the server received a packet from the client, the clock on the client had already gone ahead - everything related to compensating for this garbage. Ping (latency) "to the client" may differ from the ping "from the client".
4. Isolation of clients from each other: none of them should receive events about the whole world. Events on the client should only fall if they happened near it.
5. https://habrahabr.ru/post/302394/ -- an article about synchronization methods. At the end, the most interesting method is described with the accumulation of history on the client, throwing out part of the history upon confirmation of its execution on the server.