🔹 Before Go Modules (pre–Go 1.11)

• Go only had GOPATH mode.
• All your projects and dependencies had to live inside $GOPATH/src.
• Example: if $GOPATH=/home/maelton/go, then your project would be in /home/maelton/go/src/github.com/maelton/myapp.
• Dependencies were downloaded into $GOPATH/src too (source code, not binaries).
• This was restrictive because you couldn’t easily work with projects outside GOPATH.

🔹 With Go Modules (Go 1.11+, default since 1.16)

• You can now create a go.mod file in any directory, and Go treats that directory as a module root.

• Dependencies are not downloaded into your project folder anymore, but instead cached in a global location:

  $GOPATH/pkg/mod
  

  Example:

  ~/go/pkg/mod/github.com/gin-gonic/[email protected]/
  

• Compiled versions of packages (object files) go into:

  $GOPATH/pkg/
  

• Your project only has go.mod and go.sum, not the actual dependency code.

🔹 When you run go get or go build

1. Go fetches the source code of the dependency (from GitHub, GitLab, etc.) and places it in $GOPATH/pkg/mod.
2. Go compiles it into a cached binary form for reuse.
3. Your project imports from the cache, not from inside your project.

So:

✅ You download the source code, not just the binary.

✅ It goes into a global cache (pkg/mod) instead of your project folder.