The history of riddles is long and deserves far more words than I'm going to put down here, but no introductory article on riddles would be complete without covering it to some extent. Riddles go back to some of the oldest written cultures - our oldest riddles are Babylonian era and have sadly long since lost their answers. One of the most famous riddles to this day is the Riddle of the Sphinx: what walks on four legs in the morning, two at noon, and three in the evening? The answer is a human: crawling as a baby, standing in their prime, then walking with a stick in old age (though one seventeenth century luminary did valiantly attempt to argue for "the philosopher's stone" as an alternative answer!) The association of riddles with the sphinx, and the myth of the sphinx killing those who could not answer, may have been a factor in associations between riddles and danger that later found their way into modern works of fantasy.
Moving into the post-Classical era, the Saxons were also lovers of riddles, which probably also shapes their modern associations with a historic world of fireside storytelling. Saxon riddles often had two answers, with a simple "correct" answer lying underneath a heavy double-entendre. Take a look at this one:
I heard there's something growing in its nook, swelling, rising, and expanding, pushing against its covering. I heard a cocky-minded young woman took that boneless thing in her hands, covered its tumescence with a soft cloth.
Anyone who guessed "dough rising" - congratulations, that's the right answer. Though you'd be forgiven for certain other guesses! You'll also note that this is a lot longer than some of the other riddles we're discussing. It's actually quite short by the standards of Saxon riddles, which often tended to be long and discursive and include many obliquely described aspects of the creation or manufacture of common items. The focus on common items is an important aspect of riddles; whatever a riddle is about needs to be something that the audience will reliably latch onto, so it needs to be an item or concept that will not only be easily recognisable to the reader but of which the details needed to get the riddle will also be known. The modern riddle I take what you receive, but surrender it by raising my flag, for example, is very hard for many Europeans to get as it relies on the reader being familiar with the style of outdoor mailbox common in the US that raises a side-lever (the flag) when it opens.
It's worth thinking about the functions of riddles in past societies and cultures. Whilst they tend to universally be something of a game, the associations in different cultures about what function that game had and when it was played are pretty variable. Many societies seem to have had direct riddle contests as a sort of intellectual sport, probably including at symposia parties in the ancient Greek world but also in many cultures since. Longer riddles like those of the Saxons could be used as a framed way of discussing or presenting information more generally; a longer riddle that goes right through the production process for a certain item can give room for additional useful information to be added. Riddles could be put to innovative uses, too. In 12th Armenia, the Catholicos Nerses Shnorhali used riddles as a religious teaching tool, creating a wide variety of riddles with biblical references as a way of getting his flock engaged with the texts he wanted them to read. This is an interesting reverse of the problem of the reader needing cultural familiarity - using a riddle as a tool to create or provoke cultural familiarity by needing the reader to know the text to find the answers.
It would be wrong to leave this section simply looking at western examples though. Riddles are a worldwide phenomenon, and have been attested from around Africa, across Asia, and into the Americas, though our knowledge of traditional native American riddles is comparatively patchy. The following: Riddle, riddle, I'm no priest or king, but I've clothes as fine as anything is a rough translation of a Bugtong, a Filipino riddle - the answer is a washing line. The bugtong is apparently usually used as a game at a funeral wake, giving yet another context and association for riddling. Chinese riddles are also numerous - they have a range of visual options for puns thanks to the diversity and complexity of Chinese characters which are unavailable in many simpler alphabet systems. Chinese riddles were mostly collected in the modern era; the survival of older riddles from many cultures is likely to have varied depending on how literary the cultures were and whether riddles were considered a folk game unworthy of higher study, or a worthy literary pursuit.
