Electron is an open source framework that can help you build apps for Mac, Windows, and Linux. If you are able to build a website with Electron, you can also build desktop apps. Currently it is labeled as Electron 1.0.
You might not have realized it but we are already using apps that use Electron as its framework. Some examples are; Calypso (WordPress desktop app), Nylas N1 (email client), GitKraken (git client), and even the popular Slack.
Electron 1.0 comes with API stability and usability improvements. It makes it even simpler to explore and learn about Electron APIs with a new app. It also improves upon a couple of other tools that help developers along the way.