Apache License facts for kids

The Apache License is a special set of rules for using computer software. It's like a permission slip that lets people use, share, and change software made by the Apache Software Foundation (ASF) and others. This license is very flexible. It lets you use the software for almost anything you want. You can even make changes to it and share your new versions. The best part is, you don't have to pay any extra fees or "royalties" to use it. Many software projects, not just those from the ASF, use this license.

How the Apache License Started

The Apache Group, which later became the Apache Software Foundation, started making software in 1995. One of their most famous creations was the Apache HTTP Server. At first, their license was a lot like another old license called the Original BSD license. It had a few simple rules, but it also said that if you changed the software, you couldn't use the "Apache" name for your new version.

In 1999, some changes happened with the BSD license. They removed a rule that made people mention the original software in their ads. Apache followed this idea in 2000. They created the Apache License 1.1. With this new version, if you made changes to Apache software, you only had to mention the original in your documentation, not in your advertising.

Then, in 2004, the ASF made a big change and released the Apache License 2.0. They wanted to make it even easier for other software projects to use their license. They also wanted it to work better with software that used the GNU General Public License (GPL). This new license also made it clearer how people could contribute to the software. It even included rules about patents, which are like special rights for inventions.

What the License Allows You to Do

The Apache License is known as a "permissive" license. This means it gives you a lot of freedom. Unlike some other licenses, it doesn't force you to share your changed software under the exact same Apache License. You can often use a different license for your new parts.

However, there are still some important rules:

• You must keep the original copyright, patent, and trademark notices in the software. These tell you who created the original parts.
• If you change a file, you need to add a note saying that you made changes to it.
• Sometimes, the original software comes with a special text file called a `NOTICE` file. If it does, you need to include a copy of this `NOTICE` file with your changed software. This file usually has extra information or thanks to other contributors.

These rules help make sure that everyone knows where the software came from and who helped create it.

Apache License 2.0 and Patents

The Apache License 2.0 has a special part about patents. A patent is a legal right that protects an invention. This part of the license helps protect people who use the software. It basically says that if someone contributes code to an Apache-licensed project, they are also giving you permission to use any patents they might have related to that code. This helps prevent legal problems later on.

How it Works with Other Licenses

The Apache License 2.0 is considered a "free software license" by groups like the Apache Software Foundation and the Free Software Foundation. It's also compatible with version 3 of the GNU General Public License (GPLv3). This means you can take code that uses the Apache License 2.0 and combine it with code that uses GPLv3. The new combined software would then be under the GPLv3.

However, older versions of the Apache License (before 2.0) are not compatible with any version of the GPL. This means you can't easily mix code from those older Apache licenses with GPL code. The Free Software Foundation actually recommends the Apache License 2.0 because of its clear rules about patents.

See also

In Spanish: Apache License para niños

• Comparison of free and open-source software licenses
• Software using the Apache license (category)