It is considered a matter of traditional (Western) etiquette not to ask a woman her age. However, the exact reason why this is thought to be rude is not clear. Many people have different explanations as to why asking a woman her age is not polite. This article sets out some of those common theories and explores the assumptions behind them.

According to some standards, this question only really violates etiquette if the asker is a man, not another woman. One of the reasons has to do with the idea that women usually have an earlier "expiration date" than men. In other words, a woman will probably stop being considered attractive at a relatively early age as compared to her male counterpart. Thus, the "burden" of appearing young tends to be placed on the woman, when it comes to interaction between the sexes. A man will find it easier to assume that he is not too old, while it is riskier for a woman to make the same assumption. The woman might be nervous that, if she does not give the "right" answer—i.e. happen to be young enough—then the man will simply dismiss her from his attention.

Akin to the above reason is this other explanation: the asker is implying that woman in question has failed in her "duty" to look young. Is this an exaggeration—the idea that women can feel obligated to stay young-looking? Perhaps not. Despite the rise of the stereotype known as the metrosexual (thank you very much, Mr. Beckham), the industry of beauty and rejuvenating products is still dominated by women. This state of affairs may give the impression that women have a responsibility not to grow old, or that they should stay out of sight when they do (notice the criticisms of Hillary Clinton's "old" appearance leveled at her during her Presidential campaign, though similar comments were hardly ever pointed at John McCain, who is older).

Another reason has to do with the (supposedly) stricter expectations of propriety on women. Women must be more careful to act their age—or at least, the age they would like to be seen as. The rules for men may be more lax: a young man may carry himself with the entitlement of someone older, and an older man is free to act childishly. Asking a woman her age may be a veiled accusation that she is not acting appropriately, and is behaving in a way that is too young or too old.

It is a sad set of circumstances that this state of affairs gives the beauty/anti-aging industry a bad name, as perpetuating sexism and ageism. Still, there need not be anything wrong with wanting to look and feel youthful, particularly if it is connected with a wish to be healthy and active, instead of "fading away" like society dictates that older people do. Perhaps, when we develop healthier outlooks on the phenomenon of aging, it will no longer be a sign of bad etiquette to ask a woman how old she is.