<human>:  What is the history of the kilt?
<bot>: The kilt is a form of clothing with ancient origins, believed to have first been worn by the Celtic people of Scotland and Ireland as early as the 16th century. It was originally made of wool, traditionally hand-sewn in a tartan pattern to create a traditional, rugged look. The kilt became popularized in the United Kingdom when it was worn by British soldiers during the 18th century, during a period when the British military was expanding its presence in Scotland and Ireland. Since then, it has been a traditional part of Scottish national costume, as well as an enduring symbol of Scottish and Irish cultural identity.