Selections in Photoshop on the web allow you to edit specific areas of an image with precision. This tutorial covers different selection tools, including the Marquee tool for geometric shapes, the Lasso tool for freehand selections, and the Object Selection tool, which detects and isolates objects automatically. Once a selection is made, indicated by marching ants, edits will only affect the selected area. Selections can also be modified, expanded, or used to create layer masks for advanced edits, such as removing objects from an image. With these tools, Photoshop on the web makes precise editing quick and efficient.