What the @#%$ is a whip Stitch?!?!?!

I log on to 365 to catch up on my card making, since it is a prize week after all, and I'm left scratching my head. They tell us to Whip Stitch a card... what the heck?!?!?!?!? I assumed that the example that was posted knew what she was doing, so I totally CASE-d it!!! Yeah, I'm like that! ha ha ha But I didn't know what else to do! So here's my card:
So I guess I'm all enlightened now. I can whip stitch with the best of 'em! ha ha ha But I'm still unclear on why anyone would want to do this to their cards.... humm, some things in life just have to remain a mystery. TTYL