This is basically a "loss leader" business model -- take a loss on selling milk, hoping that brings in customers to buy your cookies. So in open source, there

This is basically a "loss leader" business model -- take a loss on selling milk, hoping that brings in customers to buy your cookies. So in open source, there are some things you can do -- sell support (where the software is the thing that draws in the need for support). Second thing is sell a service that ties into the open source code. Third is have the core product open source, with paid add-ins. The paid add-ins is even more attractive if there is a third-party requirement that prevents the additional functionality from being open source (i.e., if you want to add Oracle database support to your backup code, you need to license [under NDA] a development kit from Oracle; or things like patented plugins for specific video streaming formats on a media app).