Learn in the textbookSoftware Distribution and Usage Models
DefinitionOpen source software (オープンソースソフトウェア, OSS) is software whose source code is published so that anyone may modify and redistribute it under the terms of its license.
ExplanationSource code is the content of a program written in a form people can read, and because it is published, users can study how the software works and change it. An OSS license may not shut out particular people or fields of use.
AnalogyIt is like a recipe whose method has been made public. You may change it and pass it on, but you follow the rules attached to the original, such as keeping the author's name.
Memory hookThe "open" means opening up the contents (the source) for anyone to see.