What Is Image Watermarking?
A watermark is a text or logo overlay stamped onto an image — usually semi- transparent — to mark ownership or discourage unauthorized reuse. It's common for photographers sharing previews, businesses branding product photos, and anyone posting images publicly who wants their name attached to the work. The overlay is drawn directly onto the image's pixels using the Canvas API, at whatever opacity, size, and position you choose, so the result is a single flattened image file ready to share or publish.