How are snaps attached to fabric?
The caps (and posts) have a long prong that stick out, while the sockets and studs each have a center hole. The prong is poked through the fabric and then comes up through the hole of a socket or stud. A tool is then used (either a press or pliers) to flatten the prong. When the prong is flattened, it forms a barrier which holds the socket or stud in place.