Other responses have pointed out that many people just like programming, so they contribute without requiring payment. There's another reason that might appeal

Other responses have pointed out that many people just like programming, so they contribute without requiring payment. There's another reason that might appeal to your practical side which is basic economic utility - everyone gets to benefit from the specialized contributions of others.[1] If there were no open source projects and you wanted to write the latest trendy web app, you'd have to either write or buy all of it which is horribly time-consuming or expensive. With open source, you can run a free web server and a free database server on a free OS and just write the business logic and presentation. For the latter part, you can leverage free application and javascript frameworks to speed up development. At the end of the day no one cares if your application uses C/Postgres, Ruby/MongoDB, or C#.NET/MSSQL; they care if the application is useful. So all this contribution to open source helps everyone achieve the end goal (useful app) without getting lost along the way (implementing or buying the entire stack). So why do people give away their free time and hard-earned, valuable skills? Everyone benefits. [1] http://en.wikipedia.org/wiki/Gains_from_trade http://en.wikipedia.org/wiki/Gains_from_trade