History...
The first cocktail dress was presented as the knee-long garment made from silk or chiffon and decorated abundantly with embroidery, stresses, pearls and a lot more. Quite harsh fashion rules dictated the length of the dress the skirt of which was short enough, absence of sleeves and the collar. Moreover, the fashion designers followed the rule of balance when the top of the cocktail dress is too open, then the skirt should have been strict and closed, and vise versa.
Traditional cocktail dresses were worn with lots of accessories like small purses with the chain holder decorated with spangles to hold only a powder-case and other small belongings, shoes to match the color of the dress or the purse, elbow-long gloves that accentuated the elegance of a woman hand in absence of sleeves and little flirty hats. These accessories as must-have to the cocktail dress were well practiced till the middle of 60s.
Cocktail parties that were closed functions for the other times moved to the other level and were open and available for anyone in 30s, and not only ladies for high society but all women of any status and age afforded themselves cocktail dresses. That came after a little black dress was invented in 1926, and the black color was acknowledged as the appropriate and elegant solution for any cocktail dresses.
Yet, new life was breathed into the cocktail dress in the post-war period thanks to the fashion for ethnic patterns and exotic fabric that took place in the end of forties. Post-war cocktail dresses were eye-catching and fascinating with all those spangles and glittering embroidery following the principle when the more it glitters, the better.
The fashionmongers of that time enjoyed puffed skirts and low-neck, pencil-skirts with the embroidery on the collar, and tightly-fitted dresses to emphasize good shapes. A must-have accessory to go with the dress is still a small purse or clutch to match the dress in the color, shoes and gloves.
During 60s the cocktails dresses were forgotten for some time that went on within several decades. Swinging population of the 60s completely ignored the cocktail dresses as something that is not comfortable and constraining movements, and more extravagant and stunning clothes appeared to replace those dresses in the style of new tendency, disco.
Cocktail dresses revived in the 90s again. Since that time couturiers and designers who ignored cocktail dresses for over several decades re-launched collections with vintage clothes, as well as fashion brands. Today, a cocktail dress is a must-have for the most designer collections no matter of the season.