If you have a social media account or an account at one of the photo sharing websites, you need to make sure that your photos are published using the appropriate license. Flickr allows you to offer your photos under a specific Creative Commons license which allows those downloading the photos to pass them on or use them under certain conditions.
It can be confusing, so the rule of thumb is to make sure that if you choose a non-standard license which allows people to use your photos in any way, make sure that you understand what you’re allowing.
For example, Flickr has started allowing their website visitors to buy posters from a selection of “millions” of photos published on their service. The photographer who has published the photo to Flickr under a Creative Commons Attribution license doesn’t get paid a penny.
Why? Because that license allows anyone to download and sell the photo, provided that they say where the image came from. From the summary of the Attribution License (highlighting mine):
You are free to:
Share — copy and redistribute the material in any medium or format
Adapt — remix, transform, and build upon the material
for any purpose, even commercially.
It’s also important to note that once someone has downloaded an image under these license conditions, the photographer can’t revoke the terms for that specific photo at a later date. Again, from the license summary:
The licensor cannot revoke these freedoms as long as you follow the license terms.
That may seem pretty unfair to the photographer, but don’t forget that the photographers have gone out of their way to specifically choose this option. The default choice is “All Rights Reserved”, which means that no-one has the legal right to download, re-use and even sell the image.
If you have a Flickr account, you can check the license settings for your account here (when you’re logged in).