When talking about historical dances, the word refers almost solely to dances of the nobility and upper classes (i.e. courtly dances). Of course, the "common folk" had its own dances, but there is very little information about what they might have been up until the 19th century.
Most historical dances are referred to as "Italian", "English", etc. However, these dances were part of the pan-European court culture in the sense that most dances, or at least the dance styles, were known in most European courts. Queen Elizabeth I of England, for example, is known to have enjoyed dancing, skilfully no less, Italian dances of her era. The so-called "nationalities" of dances primarily refer to the country or language of the source they are now known from.
Pietro Longhi: Ballando Lesson, 1741 (detail)
Historical dances are fundamentally different from modern dances in that a piece of music is practically always matched by a specific choreography, and vice versa. So, for example, musicians do not play a waltz, where the dancers can take any waltz steps they want, but instead they play a specific dance tune that always has exactly the same steps and figures done to it. This has enabled the dances to remain largely unchanged for hundreds of years, over thousands of kilometers. An English dance may have been danced rather "intact" 100 years later in France, or four hundred years later in Finland.
There are essentially two types of source material for historical dances: dance manuals written for teaching purposes and people’s personal notes on dances. They explain the choreographies with varying degrees of accuracy. The manuals are, obviously, more accurate, but even they are not shining examples of clarity, especially for us nowadays. However, similar steps, figures and sections have been used in different dances, so exploring multiple sources can help you better understand what patterns and steps each text has attempted to describe, and ultimately end up with a functional and danceable reconstruction.
In the Renaissance sources, floor patterns are always described verbally only. At the mid-17th century "break point", the idea of presenting a choreography as a graphical diagram was invented. Consequently, the sources of Baroque dance are, as a rule, graphic illustrations. These are often more accurate and less ambiguous, but for the uninitiated, also more laborious to interpret and understand.
In addition to the choreography descriptions, the preserved dance manuals always include at least the melody of the song to which the choreography is written. As for people’s personal notes, they occassionally include some musical notes or mention by name the song used. If neither musical notes nor the name of the song are mentioned, we can still use the name of the choreography to do some detective work: Since choreographies are usually named directly after the song (or vice versa), useful music can sometimes be found by searching for songs of the same name in published music books and the like.
Jan Steen: Dancing Couple, 1663 (detail)