You shouldn't ever post an image directly from another site. You should post a link to a page that contains the image. If people want to see it, they can click to see the page that contains the image and see it in context. It's partly a courtesy thing, and partly a copyright issue.

If you're storing an image locally, the original source loses the ability to modify the image and have it be updated directly. If you paste a link to their image only, you're not letting people see the page that the image was stored in (it's rude). And if you paste the link directly into a forum page, you're making every person who loads the page also load the image. It's a severe bandwidth hog, and considered very rude.

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Fraser Cain
Publisher
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