A watermark shows who made a picture and discourages people from reusing it without credit. Here is where to put it, how strong to make it, and how to add one for free.
What a watermark does
Anything you post online can be saved and reposted. A visible name or web address on the picture travels with every copy, so viewers can find the source, and it puts off casual reuse. It is not a lock: a determined person can crop or edit it out. Think of it as a signature rather than a security system.
Where to place it
A corner, usually the bottom right, is the conventional place and disturbs the image least. The drawback is that it can be cropped away. A large, faint mark across the middle is much harder to remove, which is why photographers use it on proofs sent to clients. Choose the corner for finished work you want to look good, and the centre for previews you want to protect.
Size, opacity and color
The mark should be readable when you look for it and easy to ignore when you do not. An opacity between 30 and 60 percent usually achieves that. Use white on dark pictures and a dark color on bright ones.
Add a text watermark in three steps
Open the Watermark Image tool and upload a photo. Type your text, for example © your name or your website, then set the size, opacity, color and position while watching the preview. Download the picture as JPG or PNG. The photo is processed in your browser, so the unmarked original never leaves your device.
What to write
Keep it short. A name, a social handle or a domain is enough and stays legible at small sizes. Use the same text and position on all your pictures so people come to recognise it.