These rules dictate where, when, with whom and in what manner we flirt.
We generally obey these unofficial laws instinctively, without being conscious of doing so.
Flirting in drinking-places is, however, subject to more conditions and restrictions than at parties.
According to some evolutionary psychologists, flirting may even be the foundation of civilisation as we know it.
They argue that the large human brain – our superior intelligence, complex language, everything that distinguishes us from animals – is the equivalent of the peacock's tail: a courtship device evolved to attract and retain sexual partners.
This is largely because they are full of young single people making their first attempts at mate selection.
Learning-places are also particularly conducive to flirting because the shared lifestyle and concerns of students, and the informal atmosphere, make it easy for them to initiate conversation with each other.
Flirting is much more than just a bit of fun: it is a universal and essential aspect of human interaction.