In Photoshop, tolerance defines the range of colour or brightness values that are considered similar when using tools like the Magic Wand or Paint Bucket. A higher tolerance includes a wider range of pixels for selection or fill, while a lower tolerance restricts it to pixels very close in value.
Photographers and digital artists use tolerance to make precise selections, isolate areas for editing, or apply colour fills accurately. Understanding and adjusting tolerance settings allows for more control in image manipulation, ensuring cleaner edits and professional-quality results.