Quick answer: A magic ring, also called a magic circle or adjustable ring, creates a centre that can be tightened after the first round of stitches.
Magic Ring Crochet Steps
Lay the yarn tail across your fingers, wrap the working yarn to form a loop, insert the hook under the first strand, catch the working yarn, and pull up a loop. Chain only if the pattern requires it, work the first round into the ring, then pull the tail to close the centre.
Count the First Round
The loop on the hook does not count as a stitch. Count only the completed stitches worked into the adjustable ring. Place a marker in the first stitch when the pattern continues in spiral rounds.
Close and Secure the Ring
Pull the tail gradually while supporting the first round. Weave the tail through several stitches in changing directions after the piece is stable. A ring can loosen if the tail is trimmed too short or not woven securely.
Magic Ring Problems
If the ring will not close, check that the stitches were made around both the loop and tail. If the yarn breaks, reduce pulling force or use the chain-two alternative for delicate or highly textured yarn.
When to Use a Magic Circle
Use an adjustable ring for amigurumi heads, limbs, hats, motifs, and other projects that benefit from a closed centre. Follow the pattern when an intentional opening or different foundation is required.
Use the instructions and terminology stated by the pattern you are following. Make a swatch when gauge or finished size matters.