Unity’s Package Manager

A package is a container that stores various types of features or assets, such as:

• Editor tools and libraries, such as a text editor, an animation viewer or test frameworks.
• Runtime tools and libraries like the Physics API or a Graphics pipeline.
• Asset collections, such as Textures or animations.
• Project templates to share common project types with others.

Packages deliver a wide range of enhancements to Unity through the Package Manager. In the Editor, you can access the Package Manager window through this menu: Window > Package Manager.

Note: The Package Manager also supports viewing any Asset Store packages you have already downloaded or imported from the Unity Asset StoreA growing library of free and commercial assets created by Unity and members of the community. Offers a wide variety of assets, from textures, models and animations to whole project examples, tutorials and Editor extensions. More info
See in Glossary. For more information, see Asset packagesA collection of files and data from Unity projects, or elements of projects, which are compressed and stored in one file, similar to Zip files, with the .unitypackage extension. Asset packages are a handy way of sharing and re-using Unity projects and collections of assets. More info
See in Glossary.

How Unity works with packages

When Unity opens a Project, the Unity Package Manager reads the Project manifestEach Unity project has a project manifest, which acts as an entry point for the Package Manager. This file must be available in the <project>/Packages directory. The Package Manager uses it to configure many things, including a list of dependencies for that project, as well as any package repository to query for packages. More info
See in Glossary (1) to figure out what packages to load in the Project. Then it sends a request (2) to the package registry server (3) for each package that appears as a dependency
See in Glossary in the manifest. The package registry then sends the requested information and data back to the Package Manager (4), which then installs those packages (5) in the Project. Each Project has its own manifest which lists the packages to load as “dependencies” of the Project.

If you want to include a package in your Project, you must update the Project manifest to include it in the list of dependencies. If you want to, you can modify the Project manifest directly, but it is safer and easier to let the Package Manager do that. For more information on using the user interface, see the documentation for the Package Manager window.

How to use the Package Manager

The Package Manager uses three interfaces to communicate with users, manifests, and registries:

• Unity Package Manager added in Unity 2018.1 NewIn20181