Finding images online can seem easy, however images that are found with a quick Google search may not contain all of the artist and copyright information you would need to properly cite and use that image. Many of the online collections listed below are collections of public domain or open access images or those that you can use without having ask the copyright holder for permission (you should still cite these images though!). The image collections from libraries, museums, and institutions will often have more accurate metadata and information associated with the image so that you can properly cite it.
Image Source: Marsha P. Johnson pickets Bellevue Hospital to protest treatment of street people & gays. Retrieved from http://digitalcollections.nypl.org/items/510d47e3-5fa8-a3d9-e040-e00a18064a99
Below is a list of websites to search for images that allow you to search by specific rights and restrictions. However, keep in mind that just because it is on the internet does not mean that the image is in the public domain. Always check the site where you found your image for copyright and/or licensing information. Images found on Google are not owned by Google, so you should always trace your image back to the original URL in a Google image search to discover the original owner and/or exhibitor. A safe rule is to assume that any image you find online is covered by copyright unless it is labeled as having a creative commons license or is in the public domain.
Online Image Collections
Below is a list of websites to search for images that are curated by libraries, museums, and other cultural institutions.
Open Access Image Collections
Below is a list of websites to search for images that include images available for free and open access or fall within the public domain.