Heroku (pronounced her-OH-koo) is a cloud application platform which lets you host your web application and deploy updates and changes to it over the internet. It can be used for small projects , or scaled for use by enterprise software companies.

That being said, Heroku is a fairly finicky tool, and chances are you will find yourself doing something that makes Heroku upset. Luckily, everyone else who uses Heroku has also made Heroku upset, and Googling for Heroku error messages will bring up many possible solutions.