Barcelona has many curbside recycling bins that are color coded.
The blue bins take paper, magazines & cardboard (folding boxes), but NOT the plasticized cardboard juice and milk boxes. (Which go into the yellow plastic bins instead. Also, no tinfoil, because it’s metal, not paper!)
The yellow bins take all types of plastic, including plasticized juice and milk boxes, but don’t throw in plastic toys or DVD/CD-ROM’s. They also take metal cans (I’m not sure if this is just aluminum cans, or all types of metal cans.)
The brown bins are for organic remains (think compost), and all of your regular trash goes into the light gray bins. Currently very few people in Barcelona actually recycle, and most just throw all of their trash together into the gray bins.