What Am I?

I come in many different sizes, short or tall, big or small. I can brighten up the situation without really trying hard, although I can also take it away without any reason. I can be decorative or you might just hide me because I am too old to keep around, but who knows when you might want me again. I can have many different shades without changing colors. I can go anywhere with you to guide your way, or you can leave me behind where I can keep someone from falling on there face or running into something and stubbing their toe. I have an open top but I usually stay dry when it rains. You can press my buttons until I go off on you or you can take good care of me and I’ll never fail you. My tail can be long or short depending on what I am being used for, you can even give me a little helping hand with an extension, but be careful not to touch my teeth because I might bite, given the right conditions. My extended family likes to hang from walls, from the ceiling and in the shower, what am I?