Open source software comes in many shapes and sizes, but chances are you're using one of more pieces of software that are actually open source - maybe without even knowing it. For some, choosing open source is an active choice, but for others it's simply a matter of picking the best software available and it just so happen to be open source. Some examples of open source software: Linux (operating system) Mozilla Firefox (web browser) MySQL (database) Apache (web server, office suite and much more) Python (programming) Umbraco (content management system)