With Unsplash for Craft CMS, you have every image from unsplash.com right at your fingertips, in the control panel of your website.
unsplash.com is an amazing community of photographers and artists that put up their images to be used for free. High quality, high resolution images that you can use in your content and product pages right away. The unsplash license reads as follows:
All photos published on Unsplash can be used for free. You can use them for commercial and noncommercial purposes. You do not need to ask permission from or provide credit to the photographer or Unsplash, although it is appreciated when possible. - Unsplash license
You can find the plugin in the plugin store (search for "Splashing Images") or on GitHub.
Using this plugin, you can search Unsplash's huge photo archive. Thousands and thousands of images are right at your fingertips. Once you've find the image that matched with your content, you can download it to your asset library with one click.
If you have an account at Unsplash in which you've collected photos you like and collections of photos, you can link that account to your Craft site and get access to those likes & collections in the plugin as well.