Some older folks still remember the process of gathering together the references and images for their files ... and I have drawers full. Artists used to call them swipe files ... photos, drawings, and images that you used to get your drawings correct. The drawings and paintings were magnificent. The b&w photos ... not so much.
Well those days are gone with many references being readily available online. And for artists ... well the search engines and sites like pinterest bring up an awesome number of images from around the world. I still collect these to help in my work. Here's a sample.