I have sewn for over 30 years and never knew how, when using a sewing machine, the thread locked into a stitch. Your demonstration of this process was excellent - visually perfect! This information is so helpful; now thread tension is starting to make sense, which is another sewing machine function I never really got. I would love to know more! Doing something rote will work until something goes wrong. However, understanding the process opens up a higher level of learning. THANK YOU!