ELI5: Explain Like I'm 5

Protected mode

Protected mode is like a kind of invisible wall that your computer builds around important parts. It stops people from using those parts unless they have special permission to do so. You can think of it as something like a locked door. You can't open it until you have the key. The key in this case is a special type of computer code that the computer only gives to programs it trusts. This helps protect your computer from things like viruses and malicious attacks.