Identifying the font used on a website

In your browser, highlight a bit of the text.
Right click and choose Inspect

That will bring up the Developer Tools panel.
Scroll through the Styles tab until you come to a font-family property. The value set there will be the font being used.

Hi,

in addition: Best would be to show us this website in question, so we could better try to help you.

Hans-Günter

Incidentally, i'm talking about 'live' fonts, not the font in a .jpg, .png image etc. (Copying and pasting doesn't help.)