Marmite, your opinions on the matter.
It is largely a UK thing though there is a related one in New Zealand, Vegemite tastes kind of similar though you would never confuse the two and I am told there are similar things like Vitam-R (never tried it) and Cenovis (tried it many years ago for some reason).
General opinion on it is sharply divisive, to the point the advertising for it even played on it. I struggle to describe the taste (other than I like it) as anything other than like what super sour things are for sour this is for salty fermented things and almost single handedly counters the UK food is bland joke. The main problem I see is people layering it on to the tune of two knife fulls, that will make most people gag (I would struggle to choke that down and I can eat it raw) and you really just want the tip of a knife full of it and spread very thinly. Similarly it rates pretty highly on the things we all get to drag through customs to give to ex pats.
As mentioned I love the stuff, doubly so for the extra strong/XO stuff. In just looking up prices I see there is such a thing as marmite chocolate.....