An easy to understand example of OPSEC is going on a vacation, posting about it online with details of when you'll be away and probably how long you'll be gone. This information could be seen by a burglar who then decides to break into your home.

It involves being careful about what you share and how you act in order to protect sensitive information.
It originated in the U.S. military during the Vietnam War when it was discovered that seemingly innocuous actions could reveal critical strategies to enemies.

Thanks. I'll check it out