How do ESPN and other spots sites continuously keep their scores and stats up to date without the user needing to refresh for new content?

This is more of a high-level question about the relationship between client and server described above. I would have to assume this is typically accomplished by the server pushing out updates to the client, but I'm trying to wrap my head around how this happens for a massive user-base that needs to receive updates every few seconds. Any direction for technologies and design patterns I can start researching would be helpful.

I've tried a few different web searches with simlarly worded questions, but have yet to find anything useful.