Quickly finding free pictures to use on a website is more complicated than one would think.
Most professional photo sites offer a huge collection of pictures. These pictures are cheap and of good quality but I had a hard time finding something equivalent for free even in the case of commercial use. After a long unsuccessful search, I found this excellent website: www.freerangestock.com. It contains about 2000 high quality professional pictures, browseable with a search engine. It's free for commercial and non commercial uses, the website and photographers make money thanks to ads revenue.