The best ideas, like the best song lyrics, feel familiar from the moment we encounter them. (We say, “I should have thought of that!”) The Noun Project, a growing library of free, downloadable icons symbolizing objects and concepts, feels like one of those ideas. So simple it seems obvious, and so useful you can’t believe it didn’t exist before.

Founded by the husband-and-wife team of Edward Boatman and Sofya Polyakov, along with designer Scott Thomas, The Noun Project launched in 2010 with a catalog of a few hundred icons and has since grown by leaps and bounds. New symbols are submitted daily by designers around the world, and the Noun Project team recently crowdsourced the translation of its library into 25 languages. Interview with The 99%.