Overview
Selection in Photoshop allow you to create a space in a project that travels between layers and can be used to mask, edit or create a specified layer. Masking is the process of creating a space in which only one part is viewable or editable. All selections are distinguished by a crawling dashed line surrounding the area selected. Once created, Selections allow you to edit only the area within their bounds.
Tools (Quick Select, Magic Wand, Lasso tool)
Although they are grouped as the primary tool set, different selection tools create very different kinds of selections. For example, the rectangular marquee tool will only create only polygon selections where as the the quick select tool will reference the image and attempt to make logical selections based on those pixels. The following video gives a basic functional overview of how to create basic selections and what they are:
Sources: Adobe Education
Quick Select tool – The most powerful selection tool allows you to easily make selections based on information from an image.
Sources: Adobe Education
Magic Wand tool – A great selection tool for selecting pixels or areas that are the same color value.
Sources: Adobe Education
Alternative Selection Methods
There are a variety of ways in which a selection can be edited. The simplest is to use any selection tool combined with the Shift key to subtract from a selection. The following are two alternative methods: Channel isolation and Quick Mask Mode.
Channel isolation: Channels have been around even longer than layers. While they are not generally used except by print professionals, This video demonstrates a great application of this concept. (This video highlights the fact that the project is for a video-based workflow. While this is important, the application works regardless of ultimate intent.)
Sources: Adobe Education
Quick Mask Mode: This handy tool allows for direct manipulation of a selection using a brush tool. While it can create selections from scratch, it’s best use is for refining selections from other tools, such as the quick select tool. Once toggled on, Photoshop removes the standard crawling dashed line and replaces it with a tint of pink over the selection.
Sources: Adobe Education