Why deploy to a local Docker?

What is the purpose of the Deploy button when you’re on a local Docker target?

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I understand the purpose of the Deploy button for a remote Docker target…it pushes the changed files to the remote server/hosting.

But what happens (if anything) when I push the Deploy button on a local Docker target? The latest files are already there because they are on my local machine. So what am I pushing and where am I pushing it to?