I think it's pointing to a version of the repo, so npm installs the package.json of that version of the repo.

See also https://jordanbrennan.hashnode.dev/tac-a-new-css-methodology

Object property access i guess. Like

myObj["myProperty"]

If it's a function then it could be invoked,

myObj["myProperty"]()

If the key was a symbol,

myObj[theSymbol]()

Shopify has an esports team called Shopify Rebellion

I think this was what Google Plus was going for.

Instead of friend graphs (mutual) or follower graphs (directed edges), they had Circles.

Circles sound a lot like group chats.

I guess "social circles" may be a better way to model social relationships than follower graphs.