What is the primary function of a bobbin in sewing?

The primary function of a bobbin in sewing is to hold thread for stitching. A bobbin is a small, cylindrical object that is used in sewing machines to store the bottom thread that works in conjunction with the needle thread. When a sewing machine operates, the needle passes through the fabric and pulls the bobbin thread up to form stitches. This ensures a secure and consistent stitch as it combines with the thread coming from the needle. The proper functioning of the bobbin is essential to maintain the correct stitching pattern and tension, making it a critical component in the sewing process. The other choices do not capture the fundamental role of the bobbin in stitching.