in the *nix world programs are configured in two different ways, via arguments in the terminal or text based configuration files. programs which have many options like your shell, window managers, or even text editors are configured on a per-user basis with files in your home directory ~. in unix like operating systems any file or directory that starts with a period or full stop character is considered hidden, and in a default view will not be displayed. thus the name dotfiles. it's been said of every console user:

you are your dotfiles

i manage mine with gnu stow, a free, portable, lightweight symlink farm manager. it allows me to keep a versioned directory of all my config files that are virtually linked into place.

Read: managing your dotfiles »

atom is a "hackable text editor for the 21st century" created by the team at github. it's designed to be customizable, but also usable without needing to edit a config file.

this quote really sums it up perfectly:

because we spend most of our day in a text editor, the single most important feature we wanted in an editor was extensibility. atom is built with the same open source technologies used by modern web browsers. at the core of atom is chromium, the open source project behind google chrome. with that comes all the power and innovation being developed for the web. but more importantly, extending atom is as simple as writing javascript and css, two languages used by millions of developers each day.

atom.io

Read: atom editor linux install »