An image hosting service allows individuals to upload images to an Internet website. The image host will then store the image onto its server, and show the individual different types of code to allow others to view that image.


Hosting services have the potential ability to identify when and where their images are being used. When an image file is accessed, the image host is capable of logging the date and the general numeric internet address of the request.


In the case of spam (email), the messages often include unique image URLs that are specific to that message only. The unique URL is used as a tracking ID, so that the image host can identify exactly what message intended for what specific recipient has been viewed, in addition to the date and host accessing the image. This is why many email reading systems do not show images by default, to protect the reader from having their reading of spam being tracked by the email senders.