If you're looking for a stock photo for your own website, or for one of your client's websites, there are some beautiful photos online. There are two problems with many free photo sites. One, the terms are difficult to understand, and secondly, the images are not always the best quality. There are exceptions, these site often ask for donations, If you're working for a client, add a small image donation fee to the bill.
Free images generally have a Creative Commons license, which states the copyright holder's terms, such as non-commercial use or attribution required. As soon as a person takes a photo or creates an image, such as an icon, they own the copyright automatically.
If you use a copyrighted image that someone should not have uploaded and you use the image on a client's website, the responsibility and any monetary damages fall on your client, who will probably sue you. Take a screenshot of the licensing agreement on the website and give your client a copy, retaining one for yourself.
Terms on some stock photo websites are confusing. At motosha.com, the terms state in one paragraph that a person cannot use the photos for commercial purposes, and then in the next paragraph, it states that the photos have a Creative Commons Attribution license and can be used for commercial purposes with attribution.
If you need a stock photo that you can feel safe using on your personal and commercial projects, try Pexels. Their images have a Creative Commons Zero license, meaning that you can use them for personal and commercial use without attribution.
Some people believe that if you find a photo on Google image that does not have a watermark, it is free to use. Nothing could be further from the truth, unless you visit the website and determine the image has a Creative Commons Zero license.
If you can't find the right image, take one yourself. It's easier.