Understanding Bundler - to `Bundle Exec` or Not? That Is the Question

We, Ruby developers, are used to running scripts or commands with the prefix bundle exec, but sometimes it's not needed, but sometimes it is, and when it's not needed it still works just fine if we add it. So it may not be clear why we need to use it in some cases.In this blogpost I'll try to answer these questions with a little insight on what Bundler (and Ruby and Rubygems) do.