Amortentia is a love potionthat does not create actual love, but gives the drinker a powerful obsession and infatuation with the giver of the potion. It is usually either forced upon someone or covertly given. As a rule of thumb the longer a love potion awaits consumption, the stronger the effects will be, as seen in Harry potter and the half blood prince when Ron mistakenly eats a box of Chocolate Cauldrons spiked with the intense love potion intended for Harry previously bought from Weasley's Wizard Wheezes.
The potion's aroma is unique to each person who consumes it, as it smells like whatever attracts each individual, e.g. Hermione Granger says that she smells spearmint toothpaste, freshly cut grass and a piece of fresh parchment in the movies.
It can also be identified by its characteristic spirals of steam and its mother-of-pearl sheen, as noted by Hermione. Unless constantly administered, its effects eventually wear off.