copyright images

Does image copyright really a issue? If so, let's say someone pays for an image and used in their blog and I download it then use it on my blog after changing image name,alt text,etc. Does that create a copyright issues?

Hi guys, First of all, sorry for my english I hope you can help me, because i don't know anybody who know anything about niche sites... I have web about some products. And of course I never had any of these product. I can not take a photo of them. First question: Where you geting your...