Open Source & Derivative Works
WordPress & the GPL
ProCD v. Zeidenberg
USL v. BSDi
Shrink Wrap License
MS Community License
MS Permissive License
Copyleft is a licensing system, were copyright law is used to enforce the removal of restrictions on distributing copies and modified versions of a work (including software works). In copyleft licenses such as the GPL, the owner of a copyright permits others to distribute their work (in either unmodified or modified form) but only provided the distributor (licensee) also allows others receiving the work to exercise the same freedoms. For this reason copyleft licenses are also sometimes known as "reciprocal licenses".
Copyleft licenses are also sometimes described to as "viral" on the basis that once a work is placed under a copyleft license, then additions to the work are also usually placed under the same copyleft license and so on. On the whole, the viral description tends to be frequently used by critics of copyleft licenses, whereas proponents generally point to the fact that derivative works can usually only be legally created with the copyright-holder's explicit permission for proprietary licensed software.
A symbol of a reversed letter c in a full circle (as opposed to a normal letter c in a full circle) is sometimes used to indicate that a work is copyleft, although unlike the copyright symbol, the copyleft symbol doesn't have a particular legal meaning or effect.
Copyleft licenses are sometimes subdivided into subcategories based on various criteria:
Train For Linux
Online Linux Training Site. A Membership Site With A Mix Of Video And Other Training Materials. Membership Never Expires!
This site is for general information only, and represents the opinions of the authors only. This site was NOT written, NOR reviewed, NOR vetted by lawyers. The content of this site is NOT intended as, NOR should be construed as, legal or professional advice. You should consult a lawyer, if you need a legal opinion or advice on any legal matter.
Copyright © 2007-2020, Answers 2000 Limited
CERTAIN CONTENT THAT APPEARS ON THIS SITE COMES FROM AMAZON SERVICES LLC. THIS CONTENT IS PROVIDED 'AS IS' AND IS SUBJECT TO CHANGE OR REMOVAL AT ANY TIME.
CERTAIN CONTENT THAT APPEARS ON THIS SITE,COMES FROM AMAZON EU S.à r.l. THIS CONTENT IS PROVIDED 'AS IS' AND IS SUBJECT TO CHANGE OR REMOVAL AT ANY TIME.
Disclosure: Our company's websites' content (including this website's content) includes advertisements for our own company's websites, products, and services, and for other organization's websites, products, and services. In the case of links to other organization's websites, our company may receive a payment, (1) if you purchase products or services, or (2) if you sign-up for third party offers, after following links from this website. Unless specifically otherwise stated, information about other organization's products and services, is based on information provided by that organization, the product/service vendor, and/or publicly available information - and should not be taken to mean that we have used the product/service in question. Additionally, our company's websites contain some adverts which we are paid to display, but whose content is not selected by us, such as Google AdSense ads. For more detailed information, please see Advertising/Endorsements Disclosures
Click privacy for information about our company's privacy, data collection and data retention policies, and your rights.
In Association With Amazon.com
Answers 2000 Limited is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.
In Association With Amazon.co.uk
Answers 2000 Limited is a participant in the Amazon EU Associates Programme, an affiliate advertising programme designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.co.uk.
As an Amazon Associate, our company earns from qualifying purchases. Amazon, the Amazon logo, Endless, and the Endless logo are trademarks of Amazon.com, Inc. or its affiliates.
All trademarks are property of their respective owners.
All third party content and adverts are copyright of their respective owners.