Period candles could be made from two materials - tallow or beeswax. They were generally uncoloured, but there are some Renaissance examples of red, green and black candles. Tallow candles were yellow and smelly, whereas beeswax candles were nearly white and if they smelt at all, it was a pleasant smell of honey. While the poor made do with tallow candles, the rich and the church used beeswax candles refined so they were as white and pure as possible.
Modern candles are molded (giving them their uniform width), a technique that was not known until the 15th century (see www.craftcave.com). Prior to this candles were produced by techniques such as dipping, dripping or rolling, all of which were very time consuming, adding to the cost of this article. Because of this non-uniform width, most candle holders or candelabra were of the variety with a bowl to catch drips and a spike to impale the candle on. Candelabra with fitted sockets for candles are a very late period invention, as they must postdate the common manufacture of molded candles. (although you can use these to hold your new oil lamp :-))
Until the Renaissance, candles were not preferred as the main source of lighting a home - oil lamps were much more economical and equally bright, without the smell. The chief demand for beeswax candles came from the pre-Reformation church, as lighting candles was important for religious purposes.