Not to be confused with "Paperclip," The C64 Word Processor. See this node for details.

What: If webster 1913 was around in 1981, he might have said this:

paper clip (n) 
  - a device consisting of a length of wire bent into flat loops that can be
    separated by a slight pressure to clasp several sheets of paper together 

  - a spring clamp designed as a clasp for papers 

(Webster's Third New International Dictionary, Unabridged, 1981)

Styles: Paperclips have been around for a long time, and they've been constantly modified and new ideas come out every day. As such, it is impossible to list all the different types of paperclips, so I'll stick to the mainstream ones.
  • Gem - The Gem paper clip was developed by a company called Gem Manufacturing Ltd. of England. This is the common paperclip seen today, the standard "double oval" style. The Gem paperclip was never officially patented, though William Middlebrook, from Waterbury, Connecticut, patented a machine for making Gem paper clips in 1899.
  • Owl - The Owl paper clip is named as such for its eye-shaped circles. They don't get tangled with other clips, nor do they snatch at stray papers that didn't belong with the clipped stack.
  • Butterfly - The Butterfly paper clip is comprised of two triangle-shaped legs with a square top. They have a very high tension and are suitable for holding large bundles of paper together, and guaranteeing that they stay together.
  • Spring - There is a whole alternate line of spring-loaded paper clips, sometimes referred to (incorrectly) as alligator clamps. They could fill a whole node on their own.
  • Non-Skid - A variation of the Gem paper clip, the non-skid clip features many grooves to add texture and stop papers from slipping out from beneath them.
History: Paper fastening has always been a requirement in the world, and the early history of the paper clip is much the same as the early history of the stapler.

The first known fastening of papers was in the 13th century, when a short length of ribbon was placed through parallel incisions in the upper left hand corner of pages. This was followed by a seal-method, the act of connecting papers with wax and ribbons. This wax-seal method was used for nearly 600 years before any substantial improvement were made.

In 1835 a New York physician named John Ireland Howe designed and built the first truly practical machine for mass-producing solid head straight pins. In a relatively short time, straight pins were being sold by the half pound for the explicit purpose of temporarily fastening papers together.

This is where the history of the stapler and the paper clip divide.

On March 15, 1866 Johan Vaaler was born in Aurskog, Norway. The young man was known throughout the town as an inventor, and he graduated with a degree in science, electronics, and mathematics. While employed at a local invention office, he invented the paper clip in 1899. Because Norway had no patent laws at the time, it had to be approved in Germany to secure patent rights. Vaaler presented a number of designs.

Unfortunately, due to financial considerations, Vaaler had to give up on his paper clips, and lost contact with the German patent office. No patents were registered.

In 1900, Cornelius J. Brosnan of Springfield, Massachusetts was awarded the patent for the paper clip. He named it the Konaclip, but the name never stuck. Shortly afterward, Gem Manufacturing Ltd. produced their popular "Gem" paper clip.

Vaaler is generally given credit for the invention of the paper clip, though legally and on paper, it is Brosnan that gets all credit.

Somehow, though, dissent in the paper clip world doesn't quite strike fear in my heart.

Fun Paper clip Quotes: "Paper clips are gregarious by nature, and solitary ones tend to look very, very depressed." - dwardu

/msg me if you have any fun paper clip quotes
10-12 different sources used, mainly about.com and personal homepages.