How processes communicate

Program vs Process vs Thread

• Program: an application or executable file, such as Word
• Process: An instance of a process
• Thread: A separate part of a process that shares memory with it, but is run concurrently using virtual or real cores on the CPU.

Sockets

Processes on separate machines communicate using a computer network. The software interface between the process and the network is called a socket. It's made up of an IP address and a port. When one process sends information to another process, it sends it to the socket, and doesn't worry about it afterwards.

Addressing

Messages are addressed to an end system using IP addresses and ports.

Ports

Used to address specific processes on a machine. Some ports are reserved, like port 80 for HTTP requests, and 443 for HTTPS.