Great answer from p7r:

Brand value is where Coca-Cola comes in. Frequently in the UK people will say "it feels like Christmas now", once the "Christmas is coming" Coke ad with santa on lorries going through town is aired. Think about how powerful that is: people associate the celebration of the Messiah's birth, or perhaps the most intense emotional experience of the year that you can point to on a calendar, with a can of sugar water.

When you hear "Coke", you immediately think of the colours of the can, the taste of the drink, and have an emotional response which is probably very happy, positive and affirming. That's what a lifetime of Coca-Cola telling you what they stand for has done to you.

Recipe-wise, it's almost identical to Pepsi, but think about how you feel when you think of Pepsi, and how you feel when you think of Coca-Cola. That difference? That's the advertising. And it kicks in when you're stood in front of a fridge about to make a purchasing decision.

Most of the Coca-Cola sold around the World is produced under license, it doesn't come from a magic well, and is relatively easy to synthesise. So how much would the company be worth if it weren't anything special? Their entire advertising strategy is to increase brand value which also helps them whenever a customer hesitates about buying their product.

Paper: Mental Association with Brand Values is More Important than Taste

See also: Neuromarketing

Worth watching: Simon Sinek on the Power of Why