Custom firmware is like the clothes you wear. You can buy clothes from the store, but some people like to make their own clothes or change the ones they have to make them special. That's kind of what custom firmware is like for electronic devices, like your mom's phone or your dad's computer.
When you get a phone or a computer, it comes with built-in software or firmware. This software tells your device how to work and what it can and can't do. But sometimes people want to change things about their device that the built-in software doesn't allow.
That's where custom firmware comes in. People can make their own software to replace the built-in software or change it to do different things. This can let you do things like change the appearance of your device or add new features that wouldn't be possible with the normal software.
But like making your own clothes, there are risks involved with making your own firmware. If you don't know what you're doing, you could mess up your device or cause it to stop working properly. This is why it's important to have someone who knows what they're doing help you with custom firmware if you're not comfortable doing it yourself.
So in summary, custom firmware is like making your own clothes for your electronic devices. It can let you change how your device works or looks, but you need to be careful because it can also cause problems if you don't know what you're doing.