A loop fastener well-suited for attaching tags to articles of commerce. In one embodiment, the loop fastener comprises a flexible filament having a first end and a second end. In addition, the loop fastener comprises a socket, the socket having a top surface and a bottom surface, the socket being provided with a channel and a flange, the channel extending transversely from the top surface to the bottom surface, the flange extending partially into the channel, the first end of the flexible filament being disposed on top of the top surface of the socket, the flexible filament extending away from the socket generally perpendicularly relative to the channel. The loop fastener further comprises an inserting element disposed at the second end of the flexible filament, the inserting element including a plug insertable into the channel and past the flange, the plug being engageable with the flange after the plug has been inserted therepast so as to keep the plug from being easily withdrawn back past the flange.