A sewing machine creates a stitch by interlocking the top thread from the needle with the bobbin thread below. The needle pushes the thread through the fabric, where a rotating hook grabs it to form a secure lockstitch. Feed dogs move the fabric forward while the take-up lever tightens the thread for an even stitch. Proper timing between these parts is crucial—if the timing is off the machine may skip stitches or fail to sew entirely. Timing is essential for a smooth operation.