What are four basic seams and their classification?

The four basic seams are the plain seam, French seam, flat-felled seam, and overlock seam. The plain seam is the most common, joining two pieces of fabric with a simple stitch. The French seam encloses raw edges for a clean finish, making it ideal for lightweight fabrics. The flat-felled seam provides strength and durability, often used in jeans, while the overlock seam trims and finishes edges simultaneously, preventing fraying. These seams can be classified based on their construction method and the types of fabrics they are suited for.