Sometimes, you might be reading a post and there was a cool image or gif. You remember where it is and go back to look for it later and – yikes! It's gone!
[PSA posted by permission of her Regency Purple Fontitude, wtvoc]
One of the causes of this is the excessive use of bandwidth brought about by hotlinking.

Hotlinking (pardon any tech liberties I am taking with this off-the-cuff explanation) is taking the URL (www.thisimageissocuteohemgeeihavetoshareit.org/highlight-copy/#!s) from an image and posting it somewhere else (that is not an online photo album). We love to share pics (especially of hot twi-guys!) and this is one easy way to do it.
But.
When you take an image and share it, you're causing the servers on multiple websites to go back to the original website and use more bandwidth -- transmission communication energy, in a sense -- that is often limited.
And when you do it and someone else does it and someone else does it... Next thing you know, the original website's bandwidth has been exceeded (you've all seen that graphic, yeah?) and the image has been grounded.
PREVENTING THIS IS EASY ENOUGH
1. Don't take the URL of an IMAGE and link it AS AN IMAGE on another website. If you want to leave a link as a link, that's cool. Let folks go see the image on their own.
2. Instead of copying an image, consider the ever popular "right-click-save" and download the image to your computer. Then, you can upload it to an online photo album and share the image with others.
3. If this is not an option, sometimes you can load to an online album directly from the URL where the image is hosted. Just tell the online photo album to "load from URL" or some variation of that directive.
ONLINE WHATS?
Photo albums.
I personally have a paid account at photobucket. I have a free account at picasa. Other people use tinypic. Flickr is another popular spot for photo hosting.
These are accounts were you can store images you use online.
By careful use of links to images, we can do our part to prevent the Bandwidth Exceeded graphic from showing up, and show courtesy to someone else's images and storage space.:)