A liqueur is an alcoholic beverage that has been flavored with fruit, herbs, nuts, spices, flowers, or cream and bottled with added sugar. Liqueurs are typically quite sweet; they are usually not aged for long but may have resting periods during their production to allow flavours to marry.
The distinction between liqueurs and spirits is not simple because many spirits (Eg. flavoured vodka) are available today in a flavoured form. The most reliable guide to classification is that liqueurs contain added sugar, but spirits do not.
Most liqueurs have a lower alcohol content (15%-30% ABV) than spirits, but some liqueurs contain as much as 55% ABV.