For the uninitiated, Marmite is a food spread made from yeast extract, a by-product of beer brewing. Its distinctive flavour is quite difficult to describe with a single word, but it has bits of salty, savoury, and a hint of Umami. I can think of plenty people who hate the taste of Marmite, but I'm pretty crazy about it! My ajja (grandfather) has been eating it spread on toast and khari biscuit for years, and I must have acquired a taste for it somewhere along the way. Produced as Marmite in the UK, it is also sold as Vegemite in Australia and Cenovis in Switzerland with minor variations in the flavour. You can read more about Marmite here.
Here are two brilliant campaigns for Marmite, done by DDB (London), building on the love-it-or-hate-it reaction when you taste it.