Legal Definitions - copyleft

Copyleft is a type of software license designed to ensure that software, once made freely available for use, modification, and distribution, remains free in subsequent versions or derivative works. Unlike traditional copyright, which restricts the use and modification of creative works, copyleft uses copyright law to *mandate* that anyone who distributes a modified version of the software, or a new program that incorporates copyleft-licensed code, must also make their contributions and the resulting software available under the same open-source terms.

This means that if you use software or code released under a copyleft license, any new software you create that builds upon or incorporates that code must also be distributed with the same freedoms – including access to its source code – for others to use, modify, and share.

• Example 1: Enhancing an Open-Source Operating System Component

  Imagine a team of independent developers creates a highly efficient new network driver for a popular open-source operating system, releasing it under a copyleft license. A large technology company decides to incorporate this driver into their own specialized version of the operating system, which they plan to distribute widely. Under the copyleft terms, the company is obligated to release their modified version of the network driver, including any improvements or additions they made, back to the public under the same open-source license. They cannot simply integrate the driver and then keep their enhancements proprietary.

• Example 2: Building a New Application with a Copyleft Library

  Consider a non-profit organization that develops a powerful data encryption library and releases it under a copyleft license to promote secure communication for everyone. A startup company wants to build a new secure messaging application and decides to use this encryption library as a core component. Because the library is copyleft-licensed, the startup must ensure that the part of their messaging application that utilizes or builds upon the encryption library, along with any modifications or new code directly related to it, is also made available under compatible open-source terms. They cannot use the copyleft library to create a completely closed-source, proprietary messaging app without sharing their contributions to the encryption component.

• Example 3: Collaborative Development of Educational Software

  An academic institution creates a sophisticated simulation tool for teaching physics concepts and releases it under a copyleft license, encouraging global collaboration. Another university takes this tool, adds advanced features for quantum mechanics simulations, and refines its graphical interface. Due to the copyleft license, this second university is required to make their enhanced version of the simulation tool, including all their new code and improvements, publicly available under the same open-source terms. This ensures that the advancements benefit the entire educational community, allowing other institutions and students to further build upon their work.