Icon libraries that provide a large variety of images to choose from as well as rich graphics, vibrant colors, and functionality include Icons8, Noun Project, and Open Iconic. Some libraries offer well over 10,000 icons.
Icons8 features more than 19,000 icons, all created by one design team. Its work is tailored to accompany various operating systems. Noun Project pulls from various designers to form one massive icon library. Open Iconic offers multiple formats in a ready-to-use style sheet and emphasizes products that are easy to use. All sites offer free icons, while Noun Project and Icons8 offer icons for pay as well.