It’s not hard to find images to use online – just use an image search. This works well, but it’s worth noting that doing so isn’t necessarily legal. Most of the images you can find this way are owned by their original creators. This likely doesn’t matter if you’re only using something for private use, or even a school assignment, but if you intend to publish a work you need to make sure all rights are cleared.
As an artist I resent some people's assumption that original art from my abilities and imagination, which I have sacrificed a lot to develop, should somehow default to public property. If we require artists to participate in a money economy their art belongs to them. Copying images and not following the copyright owners permissions to the letter is stealing, outright. And deep pockets like Disney has taught individuals that the hard way.
My colleague Chris compared Google Image search to Bing Bing Images vs. Google Images - Which Has Better Results? Bing Images vs. Google Images - Which Has Better Results? Bing’s image search once challenged Google, offering more features and a better design. With infinite scrolling and the ability to search for similar images, Bing was legitimately better than Google at image search just a... Read More , and found Google’s results to be better. If you feel the same way, don’t worry: you can use it to find rights-cleared images. While searching for an image, click Search Tools then Usage Rights.
This is TERRIBLE! Besides being able to edit vector images like Will mentioned (which is important for those of us who don't have graphic artists available to create custom images or the budget or time to buy that service ad hoc), you could also search for style "families" (different graphics that were all in the same style). There was a huge range of files and styles in the collection and it was much faster to find what you need than to do a Bing search. Plus, you knew that everything there was free and free to use, without having to worry about CC license issues.