Message passing

Message passing is like sending a letter to your friend. When you want to tell your friend something, you write it down on a piece of paper and put it in an envelope. Then you put your friend's address on the envelope and give it to the postman. The postman takes the envelope to the post office where it gets sorted and sent to your friend's mailbox. Your friend can then read the letter and write back to you using the same process.

In computers, message passing is a way for different parts of the computer to communicate with each other. Think of your computer as a big city with lots of buildings and people. Each building has its own job to do, like a factory that makes things or a store that sells things. But sometimes the buildings need to talk to each other to get things done.

Message passing is like a letter that one building sends to another building. The message can be anything, like asking for help or sending some data. Just like in real life, the message gets sent to a mailbox (called a message queue) and then later picked up and read by the recipient.

This happens all the time in computers, especially in big programs that have lots of moving parts. For example, when you open a web page, your web browser sends a message to a server asking for the page. The server sends back the page in another message, which your web browser then displays on your screen. All of this happens in the background without you even realizing it!