As a general rule of thumb I watermark my photos because I have seen photos being lifted off website without being acknowledged and posed as someone else's work. (Someone on AR recently said that he is not a fan about it, but unfortunately I have to do whatever it takes to protect my work. But I am looking in different ways to watermark it so it's not in huge block letters. That is something for you to think about on how you want to do it).

It is also great PR for myself having my website on the photos. There are watermarking softwares out there that you can purchase but certainly you can DIY it in your photoshop. Here is a brief tutorial of photoshop:

Say you have a photograph here about hello kitty flowers, courtesy of Apple Daily of Taiwan. Open it up in your photoshop:

Select the Horizontal Type Tool that looks like the T on the menu bar. (pardon my childlike arrows here...)

Once you select the tool, place the cursor on the photo where you would want the types to show, then type in whatever you would like...

Now that you need to flatten your layers to make it ready to be saved in JPEG. Click on Layer in the menu bar on top, scroll all the way down and merge the layers. 

After that, viola! You are done!

Once you closed the layers and saved as a JPEG, it will be difficult to remove the watermarks. There are really skilled people who can do it but it will be a pain to reconstruct the photos. I have also seen people say that if they put the photos in a slide show and it can't be lifted, which is not true. I will write a follow up post later.

Hope this helps,

Cindy