Electron is an open-source framework, which is used to create desktop applications using HTML, CSS and JavaScript. In the inside, it works thanks to Chromium and Node.js.
Its original creator, GitHub, works with a wide community of developers to maintain the project, which can be found here.
One of the main perks of using Electron is that, since it's based in web technologies, it's cross platform, allowing to deploy applications for Linux, MacOS and Windows, with the same code.
It also features native elements such as menus and notifications, as well as useful developing tools for debugging and crash reporting.
Some examples of applications that use this framework, are:
... and many others.
Process that runs package.json’s main script is called the main process. The main process creates web pages by creating BrowserWindow instances. Each web page in Electron runs in its own process, which is called the renderer process. The main process manages all web pages and their corresponding renderer processes. Each renderer process is isolated and only cares about the web page running in it.