GitHub for programmers is like Wikipedia. You can edit files, see who changed what, view older versions of files, and access it from anywhere in the world, except that you are working with an encyclopedic source of data. Companies use it to build software and Websites, and hobbyist programmers use it to find and share applications.
How Does GitHub Make Money
GitHub make money through their Subscribers as they to pay a monthly fee.
The business model is very simple: If you want to share your source code with everyone, and make it public, you do not pay anything. If you need to hide your source code, because it is personal, and pass on your business, you pay.
Github has nearly 1 million users. Their conversion rate will be 1% -10%. Say that 5% of the 50,000 organic SaaS customers. If they average small program ($12/MO), which would be $ 7.2 million a year.
Naturally, these numbers could go up or down an order of magnitude, according to the number of business plans, and they sell a conversion rate. GitHub is now the largest online storage hosting to host codes for collaborative work that exists in the world.