Some free and open-source projects come with commercial-support. Usually a subscription based service is sold offering 24/7 helpdesks and full-time developers who help modifying the system to individual business needs. FOSS business models dual-license

Dual licensing is a business model for free and open source software. There is usually one copyleft community license such as GNU GPL and a commercial proprietary license sold for companies who do not want to release their source-code of the application derived from it. FOSS business models commercial-support

Freelance workers are hired for modifying systems or building software solutions. They get the money when the task is done. These short-term contracts are usual for web design or scripting tasks. According to the US Department of Labor In the past three years, companies have increased their outsourcing by 22% 7.4% of the US workforce is made up of independent contractors Approximately 10.3 million workers in the US are independent contractors

A software distribution is a bundle of a specific software, already compiled and configured. Sometimes free and open-source software distributions are sold together with commercial support. See Also linux-distribution – popular example

xt-commerce is a distribution of osCommerce which is sold with commercial support.