What are the methods of interaction between processes?

Question

Programming

Colleagues, good afternoon.

Tell me, please, what methods of interaction between processes within one OS exist?

I want to clarify that by processes I mean running instances of different programs in a single copy.
Methods are of interest to "legal", i.e. provided by the developers of both programs.

Correct me - that such interaction is implemented through sockets, and, often, through the http protocol, so that it is easy, if necessary, to spread these programs over different machines / networks.

I will be grateful for answers, additions, and recommendations of the literature.

Answer 1

file sockets, network sockets, pipes, signals.
Roughly speaking, http is also network sockets, it's just that there is already standardization of the protocol and the exchange format is usually xml / json, and in the case of sockets, they make their own package structure.
There are OS-dependent interprocessor interactions.