A needle plate, also called a throat plate, is a metal shield that can be taken off and put back on a sewing machine. This little metal shield goes over the part of your machine where the bobbin is. But some machines have special needle plates that make it easier to sew.
Some machines have seam allowance and needle placement marks on the needle plates. You can use these lines as a guide to help you sew straighter seams instead of just "eyeballing" it and hoping it turns out well. With the right needle plate, you can make perfect seams and sewing will be easier. Your needle plate can make or break a sewing project.
A sewing machine throat plate is another name for a needle plate as mentioned above. The throat plate is the metal plate under the needle and presser foot on a sewing machine. Most of the time, one or more screws hold it in place. The needle goes through holes or slots in the throat plate of a sewing machine as it moves up and down to stitch the fabric.