Open source software (also known as OSS) or sometimes FOSS (free and open source software) refers to software that can be distributed, modified and used without cost. For the end user, it means they don't need to pay (or more often these days, subscribe) for software such as a word processor or spreadsheet.

For the more curious and advanced software geek, it means you can literally take the source code, modify it in any way you feel, then re-distribute it.

It should be noted that open source software is available for both Linux and Windows operating systems. However, Linux enables installation of these free software applications from within the operating system via the Software Manager, compared to Windows, which often does not.

Examples of open source software could be as follows:

Web browsers: Brave, Opera, Firefox, Chrome

Word processors: Libre Office Writer, Apache Open Office Writer, AbiWord

Spreadsheets: Libre Office Calc, Apache Open Office Calc, Grist

Image editors:  GIMP, BitMappery