Use a browser-based tool that puts your text on the image and lets you set the wording, size, color, opacity and position before downloading. It is free with no sign-up, and because it runs locally the photo is never uploaded anywhere.
A visible name, handle or copyright line on a photo does two jobs: it discourages casual reposting without credit, and it keeps your name attached when the image inevitably gets shared out of context. Photographers, sellers posting product shots and anyone sharing drafts for review all use the same trick. Beyond watermarking, the tool works for plain labels and captions too.
A good watermark is readable without wrecking the picture. Lowering the text opacity makes it sit into the image rather than on top of it, and placing it near a corner or across a busy area makes it harder to crop out without ruining the shot. Since the text is drawn onto the image in your browser, unpublished work never has to leave your device to get marked.
Yes. You set the size, color, opacity and position, so it can be a subtle mark or a bold label.
No. The text is drawn onto the image in your browser and the file never leaves your device.
No. You download a new watermarked copy and the original is untouched.