A tamagotchi is a cyberpet. It is the size of a flatish small egg. From this egg you use three buttons to help the Tamagotchi grown from an egg...
Once its actually hatched you have to care for it by feeding it, playing games with it, turning the lights of when it goes to sleep, doctoring it when it is ill, disiplining it when its naughty and cleaning up after it.
There is a whole game to it ,like... If you leave it alone it will beep if its hungry or bored. If its hungry you can just give it a meal. But if it's bored you can either play a game with it to make it happy again or if you have less time give it a snack. But too many snacks will make it ill or fat.
The program is like a tamagotchi but with less functions. More objects on screen. You can pick it up. Oh and by the way virtually everything it says to you is in Japenese.