If all the technical terms seem completely baffling, the glossary below should help you to make better sense of them:
Bobbin: a bobbin is a small spool for holding thread. Sewing machines use two threads to make a stitch: The needle thread, coming downwards from the top of the machine and the bobbin thread coming upwards from under the needle plate. Thread is wound onto the bobbin before you begin sewing, then fitted into a bobbin case and put into place.
Buttonholes: most machines will sew buttonhole styles for you (not the actual button, that’s another feature) either in a 1-step or 4-step process. The fewer the steps, the easier it is.
Feed dogs: are saw-shaped teeth that move the fabric through the machine. As the needle stitches, the feed dogs grab the fabric, moving it under the presser foot. The term “drop feed dog” means that the feed dogs can be used in either the up or down position. When the feed dogs are down or “dropped”, you can use the machine for work such as machine embroidery where the fabric can be moved freely under the needle.
Free arm: A free arm is a cylinder on the bed of the machine which allows you to sew items such as sleeves and trouser legs. This usually works by detaching a piece on the base of the machine, leaving the arm protruding.
Integrated drop feed: the teeth drop down, making it easier to move the fabric freely - useful when quilting or embroidering.