When you take your camera and shoot pictures, whatever photographs are produced are your property. They belong to you and only you. Your work is copyrighted as soon as it is produced. This goes for any type of creative or non-creative work: writing, books, drawings, pictures, music. Anything that comes from your mind and is available to be seen or heard by others is copyrighted. Unfortunately, despite this warning, there are still quite a few thieves out there that likes to steal other's work and portray that it is theirs. While you can take legal action if you find your work to be stolen, there are a few preventative measures that you can take. The best one (and my favorite) is watermarking.
What is watermarking?
Watermarking is the act of placing text, a logo, or another image on a piece of protected work (photo, paper, etc) to protect the original image. The watermark can be extremely visible or simply transparent. It is frequently used by photographers. When a watermark is used, it is a clear signal that the photo is copyright and should not be used without permission. On stock sites, unless it is under Creative Commons license, pictures are watermarked; when someone purchases the photo for use, the watermark disappears.
Why should you use a watermark?
As stated above, using a watermark is a great preventative measure that is a clear signal that the work is under copyright and is not to be used without permission. If it is, a watermark shows who owns the copyright. You should use a watermark to protect your work. While a true thief can get around a watermark by cropping it out, you will have the proof that the original work belongs to you.
Examples of watermarks
I recently branded my photography portfolio. This means logos, colors, fonts, images, and other identifiers. During the branding, I created a couple iterations of watermarks to choose from. The first one is the watermark that I ultimately decided on.
Your watermark can be colorful or monochromatic or black and white. It can be super visible or transparent. Your watermark is yours. Make it easily identifiable. Also, if you can, put it in a location where it cannot be easily cropped out.
Note: I re-branded recently; however, the still idea is there for this post!