[OT] how do you get live output on a web page ?

["slashcomfort" <yahoo@xxxxxxxxxxxxxx>]

As en example, the comfort web module has icons on it which relect live
the state of the inputs (so when a PIR is triggered, the icons flashes)

how is this done & how would i do it on my own webpage?  In the case of
the above is it the browser continually polling the webserver for the
status (not as efficient) or does the webserver update the browser?

I realise you can make a webpage which shows current status of inputs
say and then can do a refresh to update but it doesnt look as good.

any help appreciated, im just want the terminology to research

thanks in advance

Ade