What am I?

The shape is rectangular,but is not at all.The size is not too big,but sometimes it's depend by the type.I'm hard.I have a charge inside.I am a portable thing.So,you can bring me anywhere.I am colorfull,but it is depend the type also.Because,sometimes I am just black and white.I have some dials.It is 0 up to 9,and some dials addition.I have a small scene.The located is above the dials.But,sometimes the location is middle of the dials.I have a speaker above the scene.You can use me all of time.But,it is depend the charge.If the charge give out you can't use me.I have some benefits.I am make you do anything aesily.You can use me to hear a music,watch a video.You can use me to play the game, open the internet with out to go to warnet.Some people need me to make comunication with others.So....what am I??????????????