Copyright

Copyright means that someone, somewhere has the legal and automatic right to manage the ways that written or recorded material is used by other people. The copyright symbol with a date and name is merely a courtesy to help - its absence does not imply it is not copyright.

Public domain symbol

Curiously, even Wikiversity material is copyrighted! We have to deliberately agree that anyone can use or copy material, and even then we can limit that concession for example by insisting it is not sold or published for profit.

Definitions

w:All rights reserved means that to use material, it is necessary to contact the copyright holder (usually the author) and comply with any instructions (usually provide an attribution and pay a fee). Failure is a 'civil wrong' that may mean going to court and being ordered to pay compensation.
Creative Commons offers a range of permissions, and is one of several legal definitions for w:shareware
w:Public Domain: copyright expires after a time, then anyone can do anything with that material. The period varies: in some countries, material produced by public authorities is public domain immediately it is published, while other material produced by commercial corporations copyright restrictions may be extended to 100 years or more

Questions

If you put a picture of yourself online, who owns it?
If you post a picture on Facebook, who owns the picture?

Extention

What other 'free use' copyright organizations are there (copyleft, GNU....)?

Initial reading:

Resources

/Law: studies in copyright law.