Atom is a free and open-source text and source code editor for OS X, Linux, and Windows with support for plug-ins written in Node.js, and embedded Git Control, developed by GitHub. Atom is a desktop application built using web technologies. Most of the extending packages have free software licenses and are community-built and maintained. Atom is based on Electron (formerly known as Atom Shell), a framework that enables cross-platform desktop applications using Chromium and io.js, which is also developed by GitHub. It is written in CoffeeScript and Less. It can also be used as an IDE. Atom was released from beta, as version 1.0, on June 25, 2015. The developers call Atom – ‘A hackable text editor for the 21st Century’. (Source: Wikipedia)
Go to https://atom.io/ and follow the instructions.