Too Long; Didn't Read
An integrated development environment (IDE) allows you to run code written in different programming languages. The choice is vast, and the "open source" mentality that much of the developer community also applies here. As programming is an increasingly important industry, there are also paid tools that aim to offer more freedom. Atomom, "the hackable text editor of the 21st century", is maintained by the megalith of social coding GitHub, it can do just about anything you can imagine.