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Wednesday, April 29, 2015

What is Hotlinking? - Why You and Your Students Should Avoid It

This morning Alice Keeler, Sue Waters, myself, and a few others had a nice Twitter conversation about sharing images online. In that conversation Sue indirectly brought up the topic of hotlinking. When I teach courses on classroom blogging I always talk about how to correctly use images in blog posts. One of the things that I stress in that lesson is avoiding hotlinking to images that you don't own and control online.

What is hotlinking?
In a nutshell, hotlinking is inserting a picture into a blog post through a URL rather than uploading the image file itself to your blog. You can read more about hotlinking on the Simple English Wikipedia or on Host Gator's page about preventing hotlinking to your own work.

Why you and your students should avoid hotlinking.
Hotlinking itself isn't bad if you're only linking to images that you own and control online. For example, let's say that you have a Flickr account to which you upload dozens of pictures that you took. You could use the embed code or the link that Flickr provides to post your images in your blog post.

When hotlinking causes trouble is when you link to another person's image hosted in their account or on their servers. Even if the image is in the public domain you probably don't want to hotlink to it. In fact some services, like Pixabay which hosts public domain images, block attempts at hotlinking. They block hotlinking because when you hotlink you're using more of their bandwidth than if you simply downloaded the image to your computer then uploaded it to your blog.

The biggest concern about hotlinking is not knowing exactly who or what you're linking to. As Sue implied in her Tweet this morning, it is possible that the image you linked to and the image displayed could be changed without warning. It's also possible that the link a student inserts to hotlink links back to site or host laden with malware that could then rain down havoc on your blog.
Click image for full size.

Best practices for using images in blog posts.
  1. Always try to use images that you own and upload to your blog. 
  2. If you don't own a suitable image then look for images in the public domain. Pixabay is a good place to look. Download the image and upload to your blog. 
  3. If you cannot find a suitable image in the public domain then look for images that have Creative Commons licenses attached to them. Photosforclass.com makes this easy to do. Download the image, upload it to your blog, give proper attribution to the owner of the image. 
  4. If items 1, 2, and 3 above didn't provide you with a suitable image then you can attempt to use an image under Fair Use guidelines. Fair Use is a murky water so Fair Use should be your last resort. If 1, 2, and 3 failed to produce a suitable image, repeat steps 1, 2, and 3 until you find a suitable image.