There is a "sticky back" about the size of a nickel & you stick them to the wall like stickers ~ if it helps to know ~ I have kids ages 2, 3,10 & 12 & they have these in there rooms with no issues yet :) The oldest stuck one to her lava lamp once & it did soften the plastic but still no danger :)
These butterflies make any room absolutely beautiful. They are one of my favorite wall decorations and I have and make things like that. I want tons more for every room.