Explaining Licenses

Types of Open Source Licenses

Open source licenses are legal agreements that govern the use, modification, and distribution of software source code. They play a crucial role in the open source ecosystem by defining the terms under which developers can use and contribute to open source projects.

There are two main categories of open source licenses: permissive and copyleft.

Permissive Licenses

Permissive licenses allow users to modify and redistribute software with minimal restrictions. They are often preferred for commercial use due to their flexibility.

Some popular permissive licenses include:

MIT License

• Extremely simple and permissive
• Allows reuse in proprietary software
• Requires only that the original license be included

Apache License 2.0

• Similar to MIT but includes an express patent license from contributors
• Allows sublicensing of modifications

BSD Licenses

• Come in 2-clause and 3-clause versions
• 3-clause version restricts using contributors' names for endorsement

Copyleft Licenses

Copyleft licenses require that any modified versions of the software be distributed under the same license terms.This helps maintain the open source nature of the software.

Notable copyleft licenses include:

GNU General Public License (GPL)

• Strong copyleft license
• Requires all derivative works to be distributed under GPL
• Suitable for commercial, patent, and private use

GNU Affero General Public License (AGPL)

• Similar to GPL but closes the "network loophole"
• Applies to software used over a network

GNU Lesser General Public License (LGPL)

• Less restrictive than GPL
• Allows linking with proprietary code without requiring full source disclosure