On any page of SO, the page automatically tells me if there is any update. That is, the page automatically displays the info "There is one question with update" or so.
I was curious how this is implemented. I opened my chrome browser, opened the developer tools, "Network" tag, but cannot see any request sending to the server, although there appears the info about a new question with update.
What is the technique to achieve this kind of behavior? Server push? Web socket? Does not the developer tools in browsers display such activities?
EDIT Moreover, when I click on the info "one question with update", then the new question is displayed, but in the developer tools I don't even see the question (text) being transferred. What I see is only that an icon (PNG) is retrieved from the server, which is the icon of the user asking that question. So, how is the question transferred?
