What is a rusty nail?

A rusty nail is a common construction fastener that has developed rust, typically due to prolonged exposure to moisture and oxygen. Rust is the result of iron oxidation, which not only weakens the nail but can also affect the integrity of the materials it's holding together. Rusty nails are often associated with old or neglected structures and can pose safety hazards if they break or splinter. In a broader context, "rusty nail" can also refer to a cocktail made with whiskey and Drambuie.