There are a wide variety of uses allowed when using an image licensed as a free stock photo. There is not much limit to potential uses, but you must be aware of the different types of permission allowed by the image licensor or owner. These are the main types of license you will find given to free stock images:
Non-Commercial Use only
A non-commercial use license means that you may only use the image in any way which would NOT generate revenue attributable to the use of the picture. Often for bloggers this raises the issue of whether the blog they want to use the free image on is for personal or commercial gain (for example if your blog contains AdSense or other ads), generally if your goal in writing your blog is to make money, then it is definitely commercial use. But if you write the blog for pleasure but you make a few dollars a month by placing advertisements on it, then free stock photos or illustrations with a non-commercial only licence may often be used.
Commercial/Business Use Allowed
When a photographer or illustrator has set a license on their free image to allow commercial use, then you can use the picture for your business website, blog or whatever else your business has an image-use for. As with the personal-use only terms, if you currently earn money with your site, or intend to make money with the website or blog and you use a freely sourced image, it is certainly a commercial use. Some artists granting a free commercial license for their images also set an earnings limit up-to which you can use a free non-commercial image, once you earn more than that amount you have to purchase a license for that image, usually around $50-100 a month or so.
For most free stock photos or other free images, the right to distribute the image is almost never granted to anybody using the image. Whenever you send the image to anyone else, in any media, digital, in print, or on a CD, it is an act of distribution. You may never say that any free photo is your own work or sell it to anybody else, ever. Print distribution is harder to be sure about whether your business may use a free photo. For example, if you use a free clipart in a report for college or uni, or add a photo to a power-point presentation you have made for a customer would not often count as distribution, but giving the image away to them, or selling it to your company’s client so they can use it in a presentation would certainly be an act of distribution for that image.
So can I legally use free images for my business?
Whenever you find an image which has a license allowing commercial use, that may be used for your business, or even for work done for your clients. Usually this is in the form of there NOT being a ‘no-commercial use’ or a ‘personal use only’ clause in the usage agreement for that image. It is uncommon for the usage rights for a free stock photo to explicitly grant use for commercial purposes, it’s a lot more regular for the license to specify that commercial use is prohibited.