What is the primary purpose of seam allowances in sewing?

The primary purpose of seam allowances in sewing is to provide structure and durability to seams. Seam allowances are the extra fabric between the edge of the fabric piece and the stitching line. This additional fabric not only strengthens the seams, making them less likely to rip or fray under stress, but it also helps shape the garment. Proper seam allowances ensure that seams can withstand wear and provide the necessary support for the garment's construction.

Using adequate seam allowances is essential for achieving a professional finish and for the garment to maintain its shape over time. While other factors, such as allowing for fabric stretching, enabling easy alterations, and enhancing the appearance of finished edges, are important in sewing, they are secondary to the fundamental role of seam allowances in providing structural integrity to the piece.