Thread snips are small, normally spring-loaded, scissors used for trimming threads. Their small size, about 4 inches (~10 cm) makes them easy to keep close to the sewing machine for quick access to trim the end of seams. They're also known as thread nippers, thread clippers, and thread cutters.
Unlike common scissors featuring the hinge in the middle, thread snips have the hinge in the end opposite the blades.