When sewing, more than just a regular pair of scissors are used to cut through fabric and thread. Special cutting tools are needed depending on what you are cutting - whether it be a thick piece of fabric or a hard to reach piece of thread.
These are mainly used for cutting large piece of fabrics into patterns. One of the blades is at an angle which allows for the fabric to remain flat while using the shears, making it easier to cut accurately.
This cutting tool is used for removing old stitches, buttons and opening button holes. They are small and less accurate since they only have one blade, but they are good for difficult to reach places.
Pinking shears have a zig-zag edge and are good for finishing seams. They are smaller than dressmaker shear's and more accurate.
This is a useful alternative to a seam ripper. It is also useful for trimming corners and cutting loose pieces of thread. It has two blade, so it's a bit more accurate than a seam ripper.