of the knots coming undone. This technique is commonly called "tacking." In the Midwest, tacked bed covers are referred to as comforters. Quilting is now taught in some American schools. It is also taught at senior centers around the U.S., but quilters of all ages attend classes. These forms of workshops or classes are also available in other countries in guilds and community colleges. Quilting tools Contemporary quilters use a wide range of quilting designs and styles, from ancient and ethnic to post-modern futuristic patterns. There is no one single school or style that dominates the quilt-making world. Sewing machines can be used in the process of piecing together a quilt top. Some quilters also use a home sewing machine for quilting together the layers of the quilt, as well as binding the final product. While most home sewing machines can be used to quilt layers together, having a wide throat (the space to the right of the needle mechanism) is useful to manipulate a bulky quilt through the machine when the throat is both high and long. Fabric markers can be used to mark where cuts should be made in the fabric. Marks from specialist fabric marker wash out of fabrics. Quilting rulers are usually square or rectangular measuring instruments with length measurement and degree angle markings along multiple edges. Longarm quilting machines can be used to make larger quilts. Larger machines can be leveraged so that the quilter does not have to hold the fabric. Some specialist quilt shops offer longarm services. Machine quilting needles are very sharp in order to readily pierce layers of quilt and properly sew together the quilt top, batting and backing. Hand quilting needles are traditionally called betweens and are generally smaller and stronger than normal sewing needles. They have a very small eye which prevents any extra bump at the head of the needles when you are pulling through the thread. Pins can be used in many different combinations to achieve similar results. Thimbles provide protection to fingertips. Specialist quilting threads come in many types, including different weights of thread and different materials. Cotton, polyester, and nylon threads are used in different forms of quilting. Rotary cutters revolutionized quilt-making when they appeared in the late 1970s. Rotary cutters simplify the process of cutting even slices of fabric. Basting spray is a temporary aerosol glue that can be used to spray the layers