Hats were once worn by all men and women when outside the home as an item of personal hygiene.

A gentleman tips or doffs his hat indicating a gesture such as hello, goodbye, thank you, excuse me, you're welcome, how do you do, etc. to either a man or a lady. This practice is thought to have originated from medieval times when knights would lift the visors of their armor as a friendly gesture.

A gentleman removes his hat in most indoor environments, when talking with a lady, during the National Anthem, passing of the Flag, weddings, funeral processions, dedications, and photographs. Some public lobbies and corridors are treated as outdoor spaces, in which a gentleman's hat may remain on.

Ladies may leave their hat on when indoors and during the National Anthem. However, should she be wearing a 'unisex' or men's style hat, it too should be removed during these instances.

Ladies wore brimmed hats during the day, but no brimmed hats after 5pm.

Ladies' hats were often fastened with hatpins and difficult to remove, possibly contributing to the differences in etiquette between men's and ladies' hats.