For all practical purposes, open source software is free alternative to popular expensive software like Microsoft Office, Adobe Photoshop, Outlook etc. The best way to get a taste of it is to download few open source software like Openoffice, Firefox or GIMP and try for few days. You will love it.
The free software is developed by dedicated individuals in their free time as well as by full time developers in open source companies like Redhat, Novel, IBM. All communication and collaboration among the open source developers is done through Internet.
Open source is nothing short of a silent revolution. It is a kind of those rare revolutions which can be brought by just being positive and without fighting a war or being against someone.
Vested interests of proprietary software companies do get damaged. These consider open source a threat. These companies are trying to fight back with by spreading FUD (Fear, Uncertainty, Doubt) against the open source software. A recent study says that free open source software is costing proprietary software companies (like Microsoft, Oracle, Adobe and lot of others) $60 billion per year.