There is some controversy over the origin of the Butterfly Knife, also known as the Balisong (from the name of a province in the Philippines where the use of the knife became most popular). Most sources will claim the Balisong originates in the Philippines, not due to any hard evidence as much as the steep integration of the butterfly knife into so many of Philippine fighting styles. Some of these styles claim their use of the knives dates back to 800 AD; but again, there is no concrete evidence of this (artifacts, documentation, etc).
The earliest known butterfly knives are actually French in origin, and the earliest known book on their construction and use was published in France in the early 1700s. It is hypothesized that the use of the knife spread through France and into England (where a patent was applied for it in 1880) and Spain in the 19th century. It was then brought to the Philippines (then a Spanish colony), where it was quickly adopted by native martial artists (Philippine martial arts have done this with a variety of weapons from several cultures).
Regardless of origin, the use of the Balisong was certainly perfected in the Philippines in the early 1900s. In Europe the concept of a knife whose handle split in half and pivoted to fold around the blade was a mere curiosity, a novelty to be shown off. The Philippine knife masters were the first to discover that a Balisong could actually be opened as fast, if not faster, than a western switchblade.
As explained above, the main reason for the popularity of the Balisong knife is its blinding speed in opening. A Butterfly Knife is carried in the folded position. In this position each side of the hollow hilt, which splits laterally down the center, is pivoted around the base of the blade so that it covers the blade. A clasp of some sort is extended from one half of the hilt to lock the other half and keep the knife closed.
Opening the Balisong, then, consists of three motions. One holds the knife by one half of the handle, and begins by opening the clasp with one finger. In the same motion the wielder lets go of the bottom half of the handle, allowing it and the blade to pivot down to a vertical position. One then flicks one's wrist upward, which pivots the blade out to a horizontal position, and propels the free handle up past the blade and into the palm of the wielder's hand. Although seemingly complicated, the entire procedure can be accomplished by a skilled master in the blink of an eye.
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