Share 'This has nothing to do with woodworking'

I am trying to add some shelves in my grandchildren's bedroom. The wood shelving is held up by brackets which are installed into vertical racks installed in the walls. I need to purchase the brackets, but I have no idea what you call the piece. I have attached pictures of the bracket and one of the bracket as it appears in the track . If someone could tell me the name of this thing I would apprec…