Cocktail dresses are attires that worn at cocktail parties and other semi-formal occasions. Usually the length of cocktail dresses ranges from above knee to the ankle, and the knee length and tea length dresses are more typical and full length dresses usually fall into evening dress category. Cocktail party is not as formal as prom; it is a party for people to social, with some alcohol and delicate dishes served. People chat and laugh and become friend in the party, the whole atmosphere is relaxing and merry. Thus dresses for cocktail parties are not as formal as prom dresses, usually they are of short length which makes lady appears to be slender, elegant and lively. How to choose an outstanding cocktail dress you need to catch up with the fashion trend of it. In the middle of 19th century, cocktail dresses were popular with the style of low-cut tight dresses with straps round the neck tied. Young girls were fond of stretchy taffeta, sateen and in summer hard cotton material were more popular. Till the end of fiftieth, the skirt of cocktail dresses began to be like round balloon, collocated with a delicate jacket, or suits with furs and baldachin. In this period, cocktail dresses emphasized the curvy beauty; skirts were of flowing lines and soft outlook. In the sixtieth, cocktail dresses were considered over conservative while till the eightieth, cocktail came back as the leader of fashion. Modern cocktail dresses focus on the fabric and style. Length is no longer the limits. Styles tend to be plain and graceful. Nylon and cotton are popular fabrics with soft lines which release the femininity of women’s. There shouldn’t be many ornaments, or otherwise you overall look will fall into a mess. Cocktail dresses can also be holiday dresses, especially the merry and relaxing festival parties like Christmas and the Valentine’s Day. A short length cocktail will illustrate the loveliness and vitality of girls and surely you will bring the festival more joy. Cocktail dresses are good choices for semi-formal and casual homecoming dresses. In the dancing party, you will be quite different in a cocktail dress rather than a plus size prom dresses. Because short dress illustrate youth, and long evening dress is a little too formal and feminine of girls.