ATC's are Artist Trading Cards, which are 2 1/2 inches by 3 1/2 inches, they are made like postcards and on the back of them it is written the artists name, the name of the atc, the number of them in a set, as well as the group in which you trade them. They are fun things to do, but I've not done a lot of them.
These are both embossed atc's for a swap I'm in at Just Cards. The first one is dry embossing with is a technique done using a stylus and embossing on the back to make a raised image, or in the case of this one I used a cuttlebug machine, any die cut machine will do the same thing. I used the script folder for the background cut out the stamp then used the love embossing folder to emboss the stamp.
The second of the atc's is heat embossed. So the image was stamped in black then added Black embossing powder and heat set it. Then stamped the saying and used gold embossing powder and heat set it.
Anyway that's about it.