Filing cabinet  A filing cabinet (or sometimes file cabinet in American English) is a piece of office furniture usually used to store paper documents in file folders. In the most simple context, it is an enclosure for drawers in which items are stored. The two most common forms of filing cabinets are vertical files and lateral files. A vertical file cabinet has drawers that extend from the short side (typically 15 inches) of the cabinet. A lateral file cabinet has drawers that extend from the long side (various lengths) of the cabinet. These are also called side filers in Great Britain. There are also shelf files, which go on shelves. In the United States, file cabinets are usually built to accommodate 8.5 × 11 paper, and in other countries, filing cabinets are often designed to hold other sizes of paper, such as A4 paper. Office filing cabinets are typically made of sheet metal or wood. The drawers usually use a drawer slide to facilitate opening the drawer which includes an "outstop" to prevent the drawer from being pulled completely out of the cabinet. To open a drawer on most metal filing cabinets, a small sliding mechanism known as a "thumblatch" must be pressed to release and open the drawer. Each drawer has a handle to grip and pull the drawer with. On the front face of each drawer, there is usually a label holder to allow the user to identify the contents of the drawer. Many file cabinets incorporate a keyed lock to prevent unauthorized access to the documents being stored. There are two types of locks. A "cam lock" is activated with a key that rotates the lock. A "plunger lock" is opened with a key but can be closed by merely depressing the body of the lock. The plunger lock allows a user to quickly close and lock several cabinets in a short amount of time. Some file cabinets have a metal plate or wire structure at the back of each drawer which is known as a follower block. The follower block can be adjusted forward to reduce the length of the drawer so that the file folders contained within remain upright and at the front of the drawer for easier access. Henry Brown, an American inventor, patented a "receptacle for storing and preserving papers" on November 2, 1886. This was a fire and accident safe container made of forged metal, which could be sealed with a lock. It was special in that it kept the papers separated. The invention of the vertical file remains an unsolved mystery. The Vertical Filing Cabinet section in the Early Office Museum website begins with a discussion of the erroneous conclusions by highly credentialed “secondary sources", concerning the origin of vertical filing.