Communication

The communication between the Server and the Client is basically sectioned into 2 Things.

1. Push
2. Pull

Those are 2 ways to communicate with the Server. If you know what those are, read no further, if you don't: be my guest!
"Push" is to be understood as "Something from comes from the Server without me requesting it". The Server "pushes" some information to a/some/all Clients.
"Pull" is to be understood as "I grab something from the Server". Meaning, you request something and the Server answers.

So, an example of push would be a chat. You do not request a new Chat-Message from your fried Dave, but you received it anyways.

An Example for a pull would be a user-management request. You ask the Server for your user-data and the Server sends you something. You grabed it.

Now, there are ways for this to utilize. Those can be found in the next section.