Flirting, in its purest form involves two partners and a desired, spontaneous, mutual understanding between them. This understanding can be based on a physical, emotional, social, or intellectual level.
Flirting, in its more refined levels, takes form through innuendo: a double entendre, a suggestive remark, a creative play on words, a contextual reference to a previously-mentioned experience. Less creative forms of flirting generally occur on the physical level: a woman's flip of her hair, a man who stretches during conversation, flexing all visible muscles, or a friendly form of physical contact; a soft touch on the arm, a playful slap on the shoulder.
The purpose of flirting is as myriad as those who engage in the activity. Generally, the desired result is an assuagement or inflation of ego; however, many who flirt simply enjoy the act in and of itself and seem immune to non-receptive responses.
The "flirt" is not to be confused with the "tease".