The Magic Ring, or Adjustable Ring, is a technique used in crochet to begin a work in the round.
The Magic Ring is a very useful technique when making amigurumi, the ring closes completely unlike the chain two method.
I prefer to make my Magic Ring with two loops, instead of just one, because I feel that its grip on the stitches is tighter and more secure.
Hope this helps you! If you have any questions let me know!