There are 3 main kinds of Lasso tools in Photoshop which are :
- The standard lasso
- Polygonal lasso
- Magnetic lasso
The standard lasso is a tool used for drawing freeform selections. You use this tool like a pen, you click and hold down the mouse and draw your selection on the image. To draw straight lines you can hold down the Alt key. The standard lasso is useful for making quick selections on an image, although the selected areas will not be accurate. If you make a mistake when using the lasso you can simply double-click and start your selection again.
The polygonal lasso is a tool used for drawing straight edged selection. This tool is similar to the standard lasso, but draws straight selections instead of free forms selections. To use this tool, you click the location where you want your first point for the selection, and keep clicking until you end your selection. If you want to erase the selection you can hit the Delete key. Also, if you want to draw freehand you can hold down the Alt key.
The magnetic lasso is a tool for snapping to the edges of an area of an image. To use this tool, you click the initial starting point and use the mouse to follow the edges of the object where you want to select. You can either hold the down mouse button or release the button when using this tool. When you moving the mouse it will automatically snap the edge of the object. If the lasso does not snap to the edges you can click once on the mouse, which manually adds an anchor point to the image.
To create a straight edge like the in the polygonal lasso tool you can hold down the Alt key. If you want to erase a point you can hit the delete key which will remove the previous point.
Checkout The lasso tools part 2