Cross-document messaging

Cross-document messaging is like sending secret messages between two different people living in different houses. Imagine that you and your friend live in different houses, and one day your friend sends you a message by writing it on a piece of paper and slipping it under your door. You read the message, and then you write your own message on a piece of paper and slip it back under your friend's door. This is how cross-document messaging works between different websites.

Websites are like different houses on the internet, and they have their own set of rules and security measures. But sometimes, these websites need to communicate with each other to share important information like user data or updates. This is where cross-document messaging comes in.

With cross-document messaging, websites can send messages to each other even if they are in different houses or domains. It's like creating a secret code that only the two websites can understand. This is done through a technique called postMessage, which allows one website to send messages to another website, even if they are in different domains.

So, just like you and your friend communicated with each other using secret messages, websites can communicate with each other using cross-document messaging. It's an important technique that helps different websites work together and share information securely.