A package is a container for something as small as an individual component or as large as a set of related apps. After creating a package, you can distribute it to other Salesforce users and organizations, including those outside your company.
Packages come in two forms—unmanaged and managed. In this lesson we discuss Unmanaged Packages.
Understanding Packages - https://help.salesforce.com/articleView?id=sharing_apps.htm&type=5