The internet is a great place to share with friends, families, collegues, classmates and more however, it is also a place where you can share more than you want. Whether you are a graphic artist who wants to show a potential customer what you did, or posted a great photo on your blog, they are YOURS, and yours only. You are ok with others to look, but not touch. You do not want unauthorized viewers to copy or download your graphic work and use it as their own.
I have heard a few stories of someone unexpectedly finding a photo of her daughter on a total stranger's blog. This can be scary. Although most instances are not as hair-raising, you still have one way to make it harder for viewers to take your work and call it their own, by watermarking.
There are different ways to watermark a photo, image or layout. This is one of the simplest ones.