This is important in many species for a number of reasons. It will correctly identify that both individuals are of the same species and avoid much wasted time and sperm! It may be used to establish a bond between the mating pair, which will enable efficient co-operation between the pair in raising the young. It may establish that a particular partner is capable of carrying out a particular activity satisfactorily, for example feeding of the potential partner frequently demonstrates the ability to catch and provide food for the young when they develop, even humans cross feed during courtship! Since mating is a dangerous time, during which an individual is exposed to possible danger from its intended partner, it is often the case that terminating stimuli for any possible aggressive behaviour are built into the overall behavioural pattern.

In ducks, different species have slightly different head bobbing actions which are repeated by each of the courting pair, followed by wing preening, which shows off wing markings. If a Mallard duck egg is placed into a Pochard duck nest so that it hatches with the wrong parents the poor duckling imprints on the Pochard duck and when it grows up it feverishly chases after Pochard ducks giving all of the innate behaviour patterns of a Mallard duck. The other Pochard ducks cannot respond to the odd set of stimuli being given off by the Mallard and the poor frustrated Mallard ignores other Mallards because it has been imprinted on a Pochard! This is less weird than the imprinting of hatching geese on Konrad Lorenz (a behavioural scientist) who later went swimming in their pond!