A sensory note often describe as brightness, tangy, sparkling or fruity that sets a high quality coffee apart from a regular and dull cup of joe. It is a broad term with plenty of adjectives, yet there are good and bad acids where taste is concerned.
On the scientific spectrum, acidity is measured on the pH scale, yet in coffee we think more on terms of the sensory experience - it’s bright, tangy, sour or flat? and less on where it falls on the scale.
Acidity is an extremely complex subject, that is defined all the way along the production chain, through roasting, and finally on brewing. Such factors influence the type and quantity of acidity in the coffee.
Overall, acidity plays an important role in defining the coffee profile as it adds complexity, depth, balance, liveliness, and of course flavor and aroma.