From Your Wardrobe Unlock'd on facebook
Anyone interested in history and/or genealogy will eventually have to develop an interest in clothing styles. How else can you estimate a date on an old photograph? There are other things that a piece of clothing may tell you. Take this dress shown on "Your Wardrobe Unlock'd", if it was part of a black and white picture about the best you could do, would be to say it was from a period between 1860 to 1920. It happens to be an Aesthetic style dress as it is cut loose and in a style of a renaissance dress with large sleeves.
However this photo is in color (and perhaps if this was came from someone's attic you would be able to see the colors better) The colors are green, white and violet. which as the facebook page on "Your wardrobe unlock'd" will tell you are suffragettes colors. The person wearing this dress would be wearing a secret code that other code breakers could tell she was part of the "Give Women the Vote" movement.