You might be confused with the differences between cocktail dresses and other formal dresses. Guests have freedom to decide the skirt length since a cocktail party is less formal than most events while formal dresses are what we wear to special occasions such as formal weddings, balls, charity events, etc. Also, cocktail dresses are available in a wide range of colors and patterns, on the contrary, you need to pay attention when choosing color of formal gowns. Please remember: Black is the classic and will never lost its style it remains a versatile dress for cocktail parties.