A software whose source code is freely distributed with a license to study, change and further distributed to anyone for any purpose is called open source software. Open source software is generally a team effort where dedicated programmers improve upon the source code and share the changes within the community. Open source software provides these advantages to the users due to its thriving communities −
- Interoperable on multiple platforms
- Flexible due to customizations
- Localization is possible
A software that is available free of cost for use and distribution but cannot be modified as its source code is not available is called freeware. Examples of freeware are Google Chrome, Adobe Acrobat PDF Reader, Skype, etc.
A software that is initially free and can be distributed to others as well, but needs to be paid for after a stipulated period of time is called shareware. Its source code is also not available and hence cannot be modified.
Software that can be used only by obtaining license from its developer after paying for it is called proprietary software. An individual or a company can own such proprietary software. Its source code is often closely guarded secret and it can have major restrictions like −
- No further distribution
- Number of users that can use it
- Type of computer it can be installed on, example multitasking or single user, etc.
For example, Microsoft Windows is a proprietary operating software that comes in many editions for different types of clients like single-user, multi-user, professional, etc.