The seam allowance is the width of fabric between where your seam begins and the raw edge of the fabric. A quarter-inch allowance is used by quilters for most projects. Having an accurate seam allowance is necessary for making pieces that align properly when you assemble the quilt. A seam allowance should be accounted for on pieces, full blocks, appliques, and quilt backings. Pressing the seam allowances as you quilt can help keep the allowances from getting caught in the seams or creating extra bulk.