When you're doing a photo shoot that's inspired by an historical period, it is important to have at least a basic understanding of some essential eras of history. Of course every culture and region has its own history and eras, but for this purpose we'll only briefly touch on a few essential eras which are very often referred to from British and American history.
The Ancient World (prior to the year 476 C.E.)
This period is very general, and refers to everything prior to the Medieval era, from the ancient Egyptians to the Roman Empire.
The Medieval Era (476 to mid-1400s)
The Medieval era, or the "Middle Ages", was the era dominated by feudalism. Today's highly-romanticized vision of the era is dominated by castles, brave knights and princesses in need of rescue. It was, however, also the era of deadly plagues and brutal religious inquisitions.
The Renaissance (roughly 1300s to 1600s)
This time is typically said to be a period of "classical" learning and refinement in the arts. Literature, music, painting and sculpture all took enormous steps during the renaissance. It was also the time when many true sciences were first born out of the medieval pseudo-sciences, such as astronomy growing from astrology and chemistry evolving out of alchemy. Kings still reigned in most of Europe, but feudalism was gone, and the development of gunpowder and guns had put an end to the use of suits of armor and greatly reduced the popularity of the sword, bow and arrow and crossbow.
The Georgian Era (1714 to 1830)
This was the era of the powdered wig and political revolutions. Both the United States and France, among others, had their revolutions and defeated monarchies, and white powdered wigs were the fashion for both genders.
The Regency Era (1811-1820)
The powdered wig was absolutely out-of-fashion by this time, never to return. Although this was a brief era, many of Jane Austen's novels take place in the Regency Era. If you are familiar with film adaptations of her novels such as "Pride and Prejudice" or "Sense and Sensibility," then you are familiar with the look of the Regency Era, even if the name of the era is unfamiliar.
The Victorian Era (1837-1900)
Under Queen Victoria, Britain experienced a long era of peace. As machinery began to be used to make work easier, the industrial revolution began, factories sprung up -- and smoke began pouring from tall chimneys. Fashion was dominated by tightly-laced corsets, and romantic but conservative dress. The modern concept of "Victorian" clothing is sometimes colorful, but authentic Victorian clothing was often black or gray, or sometimes white. Architecture became ornate and a bit eccentric, leading to many elaborate Victorian homes. The visual arts, typified by Art Nouveau master Alphonse Mucha, became highly romantic during the period, often depicting idealized women in elaborately draped flowing cloth. Photography was born in the Victorian Era, and eventually a custom took hold of giving a photograph of yourself to any home you visited; Victorian families prided themselves on their books full of these "cartes de visite."
The Edwardian Era (1901-1915)
During the Edwardian Era, the flowing cloth and whiplash curves of Art Nouveau went out of fashion, replaced by the stylized geometric simplicity of Art Deco. Toward the end of the era, early automobiles began to be used by some people for personal transportation instead of horses. In large cities, the first skyscrapers were built. The elaborate, heavy dresses of Victorian clothing were replaced by looser, more modest dresses, and tight corsets dropped out of fashion.
If you're interested in any of these eras, just go exploring on Google or on Wikipedia. As a starting point, here's a guide to hairstyles from many of the above eras.
Part 2 of "A Quick History Lesson EVERY Model & Photographer Should Know" will focus on the fashions of these eras, and will include visual examples of each era's "look."