The seam is simply the name of the line that is created when two pieces of fabric are joined together. If you are sewing any two pieces together, the place where they are joined is called the seam. Maybe you are wondering about the seam allowance, which is the amount of fabric alloted to sewing the pieces together. The seam allowance is the distance from the edge you put your line of sewing. In many fabrics that allowance can be very small, but some fabrics require a larger allowance to minimize fraying.
When sewing, you'll want to leave a sewing margin (or a "seam allowance") for a couple of reasons:A 5/8" margin (the standard seam allowance) between the stitch and the edge allows for a little reinforcement, and places less stress on the stitch. This will keep the stitch from breaking easily.A margin allows you to later let out the seam, in case you need more room (for example, if a skirt gets too tight, you can loosen it if there's seam allowance).
The seam allowance is needed to allow for extra fabric where separate pieces of fabric are joined together at seams. If seam allowances were not provided you wouldn't be able to join pieces together or your garment would end up being too small. If you look at the inside of a shirt, for example, you will see that the stitches take up fabric and that is what seam allowances are for.
Yes, when inserting a zipper, the zipper should be basted in first (to stabalize it while it's sewn in). When basting the zipper, it should be basted to only the seam allowance.
Yes, when sewing, you should backstitch at the end of every seam.
These measurement grooves are a seam gauge. They measure how big your seam allowance will be. As you sew, you'll align the edge of your fabric with one of the grooves. The grooves are labeled with "3/8", "4/8", "5/8", etc. If you line the edge of your fabric up with the 5/8 groove as you sew, you will have a 5/8" seam allowance, and so on.
so that the material does not fray.
The fabric between the seam and the cut edge is referred to as the seam allowance.
I think it is a part for a sewing machine
a double seam is when your sewing and you run over the stiching a second time.
Sewing a seam on the bias is sewing a piece of material that has been cut on a 45 degree angle.
Sewing margin or seam is the length between the edge of the fabric and where the seam appears. It can be as small as 1/8th of an inch or as large or larger then an inch.