Pressing it once turns it on & pressing it again turns it off.
Button B: Switches through the varying colour options.
There are a slew of different colour options, which is great, it allows for a degree of personalization as you can choose the colour scheme that you like the best.

Button C: Allows you to switch on the rotation, which makes the product more fun.

There are 3 ways to power it.
1. Power it with a USB port into an adapter and into the wall socket (Adapter not included)
2. Power it with a USB plug to computer
3. Power it with 4 AAA batteries.

Multifunction "Project" the stars and moon spinning on the ceiling and wall, rotates as the stars light up.
"non-Project" by putting the cover on and make it a night light or regular lamp.
This device comes with a cover.
Please don't forget you need to take the cover off to use it/see the stars.
The stars can rotate with mode 3 but will make slight white noise. It's not a good idea to rotate it in the very quiet midnight.
It's not so bright that it could keep children up at night, but enough for them not to be scared in the dark.

Please note that the USB Cable and the Batteries cannot be used at the same time.