How does Go update third-party packages?

Looking how actively golang packages grow and improve I wonder how the problem with package versions is solved?

I see that one way is to store third-party packages under a project folder.

But what if I install it with go get?

go get will install the package in the first directory listed at GOPATH (an environment variable which might contain a colon separated list of directories). You can use go get -u to update existing packages.

You can also use go get -u all to update all packages in your GOPATH

For larger projects, it might be reasonable to create different GOPATHs for each project, so that updating a library in project A wont cause issues in project B.

Type go help gopath to find out more about the GOPATH environment variable.

@tux answer is great, just wanted to add that you can use go get to update a specific package:

go get -u full_package_name

Since the question mentioned third-party libraries and not all packages then you probably want to fall back to using wildcards.

A use case being: I just want to update all my packages that are obtained from the Github VCS, then you would just say:

go get -u github.com/... // ('...' being the wildcard). 

This would go ahead and only update your github packages in the current $GOPATH

Same applies for within a VCS too, say you want to only upgrade all the packages from ogranizaiton A's repo's since as they have released a hotfix you depend on:

go get -u github.com/orgA/...