Public Domain vs Open Source and copyright resources

Public Domain

*How is it different from Open Source?

Types of Open Source Licenses

*Is your program copyrightable?

Citation and Resources

1.
While the designations 'Public Domain' and 'Open Source' can both imply a communal goal they are distinct and well intentioned, careful programmers should make themselves aware of the difference. Public Domain is a designation assigned and maintained by governments and can vary widely across
borders.

For instance, IMSLP the International Music Score Library Project hosts an api that allows primarily classical music researchers and performers to access a massive database of musical scores (sheet music). The server however is based in Canada where copyright ends sooner after the creator's death than in America. If this api were used in an American for profit program, there could be penalties incurred if rights are infringed upon. Another example comes from game systems. After all one of the most common applications of software is with gaming. 5e.Tools and TheTrove are resources for tabletop gaming that must be hosted in other countries due to differences in what qualifies as Public Domain. There is currently an explosion of applications designed for these games and systems and yet programmers must be careful not to use pirated sources that conflict with either their own morals or the laws of their governments. On the internet piracy is everywhere, and the term 'piracy' often covers more shades of gray than just bootlegging movies. In our work we may make programs for a wide variety of fields in which we ourselves are not professionals. This is only one way in which we must always be aware of and investigating the implications of our work.

As well, Open Source is not necessarily Public Domain.

Open Source is a label and license actively included by the author; Public Domain is a category of intellectual resources designated by governments
Furthermore, a program or document are not inherently Open Source merely by the author's decision not to include licensing, rather in the USA the lack of clarity will force it to be considered under a type of implicit copyright, one that as collaborators take and build upon your project, may soon disclude you the original creator. Some sharing sites include a form of open source documentation in their mandatory User Agreements, Github is just one of these.

2.
There are many different open source licenses . Some confer more or less freedom to use, build upon, and distribute programs built upon the original code. In general, programmatic systems cannot be copyrighted, but the literal written code and documentation and the expression thereof can. And if your code builds on someone else's earlier code, then you may be able to copyright your additions, but this would not include any original components of the base code.

3.
Referencing Code
https://runestone.academy/runestone/books/published/StudentCSP/CSPCreativity/referencing.html

Do you know if your code is open source?
https://www.publicknowledge.org/blog/do-you-know-if-your-code-is-open-source/

Types of Open Source Licenses
https://choosealicense.com/licenses/#unlicense

Public Domain Is Not Open Source
https://opensource.org/node/878#:~:text=%E2%80%9COpen%20Source%E2%80%9D%20describes%20a%20subset,with%20the%20Open%20Source%20Definition.&text=%E2%80%9CPublic%20Domain%E2%80%9D%20means%20software%20(,is%20not%20restricted%20by%20copyright.