Many people in this day and age still don't know much about the way that copyright works, so I will attempt to sum it up in as plain and concise a manner as possible. When a work is made it is under the control of whoever made it, this work is exclusive to the creator and they are the only person with the right to copy it and unless permission is explicitly given noone has the right to copy or show the work at all for any reason.
If a person says that their work is licensed under the terms of the BSD license this is not enough to actually give permission to a person to use that work as though it were licensed BSD - the person licensing it must have the license accompanying the work, be it in another file or on another page at the same website. Unless the work directly points to a copy of the license, there is no license, and the work is therefore not permitted to be copied.
Here is a list of several open source licenses approved by the Open Source Inititive, I have listed them from least to most open (most to least restrictive):
- The Bell Labs LPL (Lucent Public License) which is used for the release of Plan 9 restricts redistribution to countries which the United States holds sanctions against, this is viewed in a very negative light by many around the world because these people feel that politics and coding should not mix.
- The Sun CDDL (Common Development and Distribution License) which will cover the open source release of Solaris restricts one's ability to hold and maintain their own patents, this clause set is a matter of debate in online communities as on one hand it helps to prevent a company maliciously adding patented technology into software and suing users and distributors that make use of said software, on the other hand it is another restriction for what some view as no reason - it is implied by submitting code that you release your claim over any technologies involved. If any entity that uses works licensed under the CDDL does sue entity that contributes to any project licensed under the CDDL, that license is automatically revoked as well. These patent and revokation clauses are basically the only differences between the CDDL and the MPL.
- The Mozilla MPL (Mozilla Public License)
- The GNU GPL (General Public License) in a nutshell says that anything you distribute with GPL code must come with the code available as well and that you cannot make the code you release harder to read. This is the basic "viral license"; once applied to code it cannot be relicensed without the permission of all contributors, thus it is viewed with great distaste by companies which are looking to make an easy profit.
- The GNU LGPL (Lesser General Public License)
- The Original BSD (Berkley Software Distribution) license allows for complete usage of any code for any purpose under the conditions that proper credit is given, the license remains in tact in any binary derivatives, any advertisements for derived works must list that the work contains code from the University of California, Berkley and it's contributors and that the names of contributors and the University can not be used to promote the derived work without written permission. Pretty straight forward, no?
- The Modern BSD license dropped the condition of listing the University in advertisements, this was in part due to the number of various BSD-like licenses that were beginning to be used, they were beginning to fill up a fair amount of space in any advertisements which used multiple sources of code.
- The ISC (Internet Systems Consortium) license is basically a two-part BSD styled license which removes the fourth term where the names of contributors and copyright holders cannot have their name used in promotions without prior written consent. This is because in 1971 the Berne convention set down this term as standard for all copyrighted works.
There is another option beyond licensing a work, the creator may state that the work in question is released to the public domain, the public domain is the property of anyone that wants to use it and there are no restrictions what so ever on the work; there is no further need for permissions, no credit need be given, it is no longer the property of the creator alone. This does not, however, function globally, though this anti-licence is accepted within some nations, others do not allow for the release of property in this manner, and thus a content creator must create a licence that recreates the terms of the public domain and release their source code under it.