Proprietary software is Closed Source software - software where the source code is not released to the public, only executable code (.exe file). The source code is owned by the company and is usually a secret.
Proprietary software is often paid for (not always though) but that is not a definition you can use in an exam. To use the software you have to sign a user agreement, and accept its licences. These licences limit or prevent the modification, copying, and re-distribution (sharing / selling) of the software. In some case they may limit the usage - for example only 100 pages are allowed in some forms of web editors.
Businesses often use proprietary software rather than open source due to better customer support options and the belief that proprietary software will be less likely to have unpatched bugs.
Advantages of Proprietary Software
- Has user documentation, customer support and warranties
- Should be well tested and reliable (note the should, more companies are releasing software quicker and then fixing problems as they are found - especially true with phone Apps)
- Bug fixes, patches and updates will be released regularly
- Avoids the need to build own "in house" systems and all the cost of doing that (expert staff, development tools etc)
Disadvantages of Proprietary
- May not exactly meet a user, or small group of users, specific needs
- Older versions that are out of warranty may not be supported, updated etc which introduces security risks (examples of this are older versions of windows and internet explorer)
- It can be expensive
GIMP (graphics editor)
Firefox (web browser)
Android (operating system)
VLC (Media Player)