Legally Free Reference Photos For Your Art part 1

Pixabay
https://pixabay.com

Pixabay has over 1 million photos and videos that are nearly all published under Creative Commons Zero License (CC0). A CC0 license means you are free to use any image on the site, even if you want to go on to sell your artwork in any commercial form. The site is very easy to browse and you can quickly check for the CC0 license next

Not really any!

Unsplash
https://unsplash.com

Truly stunning photographs from professional photographers who publish all the work under the CC0 license. At the time of writing, many of Unsplash's images are also on Pixabay but if you want a more focused collection of only the very best photography, go here.

Images are published under a CC0 license so you can browse with more confidence.
Stunning images that are even better than you'll find on most paid-for stock photography websites.
A curated collection of photos that won't fail to inspire you.

MorgueFile
https://www.morguefile.com

MorgueFile was revamped not too long ago and it's now a great resource for free-to-use, high-quality photos. They don't use the CC0 license but rather an agreement of their own that works in a similar way (see it here). It's fairly standard - use the photos for any purpose, including commercial, so long as you change them in some way (i.e. make a piece of art from them - perfect!).
350,000+ professional grade images.

Pexels
https://www.pexels.com

This site cumulates free stock photos from other sites around the web. Very easy to browse lots of images quickly and all are mostly published in the CC0 license.

Not as big a collection as Pixabay.

Flickr
https://www.flickr.com

With a library of over 6 billion images and more than 3.5 million uploaded every day, you'll already be familiar with Flickr, no doubt. What you may not know about Flickr are the number of licenses its members can publish their images under, and how you filter images to show only those that you can use for your artwork.

Head over to Flickr.com and enter your search term.
In the upper left corner (on desktop devices) you'll see 'Any license'.
Change this to 'No known copyright restrictions' to show only those images in the public domain. You can use these to draw and paint from without having to give credit.
For a wider choice, choose 'Commercial use & mods allowed' but be aware that you must credit the Flickr user whenever you publish your artwork.

You'll need to give credit wherever you post your artwork, unlike other sites on this list.
You have to sift through a lot of irrelevant or poor quality images to find what you're looking for.

Wikimedia Commons
https://commons.wikimedia.org/wiki/Main_Page

You've heard of Wikipedia and Wikimedia is part of that family. It contains over 30million digital files that editors of Wikipedia can use, or that can be downloaded by you or I for other uses. Be careful though, just because it's on Wikimedia
The largest collection of free images online. If you're looking for something specific, you'll probably find it.
Many images (but not all) are published under the CC0 License or declared as public domain. Make sure you check.

Part 2 will be posted soon..