In sewing, to tack or baste is to make quick, temporary stitching intended to be removed. Tacking is used in a variety of ways: To easily hold a seam or trim in place until it can be permanently sewn, usually with a long running stitch made by hand or machine called a tacking stitch or basting stitch.
Sewing basting stitches on seams allow you to test the fitting (side seams) or placement (darts) before sewing regular stitches that might be hard to remove. Basting can hold slippery fabric together while sewing regular stitches. Basting first allows... MORE the basting stitches to be easily removed if the fabric does slip out of place.
Toy around with your sewing machine and learn how to sew different types of zigzag stitches. You can make your zigzag narrow or wide by changing the width. If you notice that your fabric gathers in a tunnel, use the pattern to the right of the zigzag which looks like a dotted zigzag. Use the zigzag stitch to finish the seams of your projects.