There are three lasso tools available in Photoshop: Standard, Polygonal and Magnetic. Each tool serves its own purpose depending on your specific needs. The Polygonal Lasso is used for selecting shapes that are not of traditional size or scope. The Standard Lasso is an all-purpose tool that requires a steady hand and careful precision. The Magnetic Lasso works much like the standard form, but with a bonus. While you are able to select the pixels you desire, Photoshop uses its Magnetic Lasso to detect your image more easily. Basically, if you have a shaky hand or have trouble making selections, the Magnetic Lasso will be your new best friend.