In sewing, you will often find yourself having to make certain adjustments to zippers depending on the garment at hand. One of the most common alterations you'll need to learn right from the beginning is how to shorten a zipper. 

You'll be surprised how often you might find yourself needing to shorten a zipper as you start making your own clothing. The most common issue that requires shortening of course, is (naturally) the zipper being too long for the designated zipper application on your garment. Due to the fact that on a commercial scale, zippers are mostly found in 5 inch increments, you'll often need to buy a long zipper and shorten it to fit your own sewing requirements. So that being said, there are really two situations that will probably  require you to shorten a zipper by hand in dressmaking: ​

Notches are clips or wedges cut into the seam allowance in order to facilitate matching and sewing the corresponding seams during garment construction. In other words, you can figure out which fabric pieces should be pieced together to  form the seam by matching the corresponding notches to one other. ​

Notches are extremely important in the sewing process.  All fabric components of a garment should be marked such that each seam is easy to piece together once the patterns are removed. It is much easier to figure out which edges should be sewn to one another when you are looking at the marked patterns. However,  once the fabric pieces are cut and the patterns are removed, a lot of important marks and lines are often lost visually, and you are left with fabric pieces that can appear a bit confusing, especially to the untrained eye. Transferring notches from the patterns onto fabric will ensure that that each edge is properly aligned and the front and back pieces are not mismatched during sewing. ​

Keep in mind- individual notches that are added to seam edges are strictly used to facilitate sewing and they should not add any form of tension release or affect the fit and look of the clothing item being constructed. Specialized notches and wedges used for release tension are cut in  groups along more curved areas of a seam, and are applied much closer to the seam-line.

​To learn more about tension release notches/wedges, check out this sewing tutorial: Clipping The Seam Allowance During Sewing: How And When To Use The Fabric Clipping Method. 

​Nevertheless, triangle or v-shaped notches take a bit longer to cut- you have to be very careful not to cut too far through the seam line in the process since it requires the cutting of a very specific triangular shape.