[zupa-hu]

One example is when you want to display live data on a website. Could be a dashboard, a chat, or really the whole site. Polling is both slower and more resource hungry.

If it is built into your language/framework, you can completely ignore the problem of updating the client, as it happens automatically.

Hope that makes sense.

[huntaub]

Interesting -- is that normally done with database updates + polling vs. something purpose-built?

[zupa-hu]

Not sure how many such solutions there are out there so no idea about the norm. I doubt polling is a real option.

You may want to search for realtime databases.