What is the Difference Between GPL and LGPL?

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The main difference between the GNU General Public License (GPL) and the GNU Lesser General Public License (LGPL) lies in how they allow the work to be linked or combined with other software. Here are the key differences:

  1. Linking: GPL requires that all derivative works be licensed as a whole under the terms of the GPL, meaning that any application linking to a GPL-covered library must also be licensed under GPL. In contrast, LGPL allows the work to be linked with or used by non-(L)GPLed programs, regardless of whether they are licensed under a GPL-family license or other licenses.
  2. Licensing for Libraries: GPL is generally for programs, while LGPL is primarily used for software libraries. LGPL allows non-GPL programs to link to libraries but still requires providing source codes.
  3. Coverage: GPL provides more protection to the software, ensuring that the source code of the application must be provided for any changes made. LGPL, on the other hand, is limited to software libraries and allows non-free programs to gain access or link to the library.
  4. Modifications: When changes are made under the GPL license, source codes are required, and changes must also be licensed under GPL. With LGPL, modifications to the software are allowed, but the original licensing terms must still be followed.

In summary, GPL is more restrictive, requiring that all derivative works be licensed under GPL, while LGPL allows for more flexibility by permitting the work to be linked with or used by non-(L)GPLed software. LGPL is primarily used for software libraries, whereas GPL is generally for programs.

Comparative Table: GPL vs LGPL

Here is a table comparing the differences between the General Public License (GPL) and the Lesser General Public License (LGPL):

Feature GPL LGPL
Protection Provides more protection to software users, ensuring they have the freedom to make changes, edit, and modify open source software, obtain source code, and redistribute it. Provides less protection to users' freedom, allowing non-free programs to link to the library, creating a combined work or derivative of the original library.
Scope Used primarily for whole software projects, including Linux. Mainly limited to software libraries.
Derivative Works Requires that all derivative works or modifications be licensed under GPL. Allows users to make changes and then return the source code.
Licensing Cannot be converted to LGPL terms. Can be converted to GPL terms.
Usage Used for execution files. Used for software libraries.

In summary, the main difference between GPL and LGPL is the level of protection and scope. GPL provides more protection for software users and is typically used for whole software projects, while LGPL provides less protection and is mainly limited to software libraries. GPL requires that all derivative works be licensed under GPL, whereas LGPL allows for more flexibility in licensing.