In Npm Script, what does it mean at the end?

see in the project today:

"start": "node --es_staging ./bin/staticServer.js &"

what does the last & mean? Its function is, although started server, but does not occupy the console, the console can still output, but server is in the startup state, where can I find the relevant documents?

Mar.28,2021

put the program in the background to run (run in background).

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