What should I put the pictures on?

I have a Compaq Presario CQ50 laptop and I'm having a little overload of pictures. I have about 500 from vacations and trips, about 150 of scenery and atleast 200 of my dogs, cats, fish, hamsters, and horses. Can I put the pictures on a CD? Or should I put them on a USB? How would I do this? Will this clear up some space? Thanks!