In most use cases, the same connection will be used across multiple packages in the same project. In early versions of SSIS (pre-2012), each package would have its own connection manager for every connection used in that package. Creating and maintaining all those connection managers could be time-consuming as the number of packages grows. Starting with SQL Server 2012, Microsoft added project connections to SSIS, allowing for the creation of connections that were accessible across all packages in a project. Instead of having to create a copy of each connection manager in every package, developers can now simply create the connection at the project level. Project connections will automatically show up in the connection manager tray for all packages in that project.
Click through to see how you can create one and get rid of per-package connections.