Marginal seat
（重定向自Swing seat）
A marginal seat or swing seat is a constituency held with a small majority in a legislative election, generally one conducted under a single-winner voting system. In Canada, they may be known as target ridings. The opposite is a safe seat.
These seats only require a small swing to change hands and therefore are typically the focus of most campaign resources. The concentration of money and manpower in areas where they will make the most difference is known as targeting.