Expanding files are types of filing systems or folders that can expand to have additional sheets of paper inserted into them. These files are typically fairly narrow in initial appearance, but utilize an accordion design that allows them to expand when needed, to allow for more paper than they may initially seem able to fit. This allows these files to easily fit into a relatively small area and keep files together in a simple way. Expanding files can then easily work in a larger area as well, by expanding and allowing additional paper to be filed in them within a larger system.
Also called accordion files, expanding files are typically used for organizing papers in a way that is simple and can be easily expanded upon. The basic design is similar to other filing folders and files, with a front and back, two closed sides, and a bottom. These files then have an open top, which allows sheets of paper or booklets to be inserted into the file. The tops of these files sometimes can be closed through an opening and closing flap, though this depends on individual designs.
Expanding files are different from other files, however, in the way the closed sides of the files are designed. Rather than a flat, straight piece of paper or board, an accordion design is used that features a single sheet of paper or plastic that is folded over itself repeatedly. This allows the sides of expanding files to expand and contract, as the folds are opened or refolded. Such files can easily fit a handful of sheets of paper, closing neatly to keep them together, while affording a user with the ability to expand the file and keep dozens or hundreds of sheets of paper together within it.
There are a number of different ways in which expanding files can be designed, though they are typically meant to be used as file inserts or folders. File inserts usually do not have any kind of top and are often meant to be part of a larger filing system; they may include tabs on the sides to fit on sliding railings within a filing cabinet. Folder expanding files are often designed with a top that can be folded back to keep the file open, or closed over the top with a loop or other system to keep them closed. Some of these files are also designed with multiple inserts that separate the larger file into numerous smaller pockets for additional organization.