Paper shredder

A paper shredder is a mechanical device used to cut paper into either strips or fine particles. Government organizations, businesses, and private individuals use shredders to destroy private, confidential, or otherwise sensitive documents.
Invention.
The first paper shredder is credited to prolific inventor Abbot Augustus Low, whose patent was filed on February 2, 1909. His invention was however never manufactured because the inventor died prematurely soon after filing the patent.
Adolf Ehinger's paper shredder, based on a hand-crank pasta maker, was the first to be manufactured in 1935 in Germany. Supposedly he created a shredding machine to shred his anti-Nazi leaflets to avoid the inquiries of the authorities. Ehinger later marketed and began selling his patented shredders to government agencies and financial institutions converting from hand-crank to electric motor. Ehinger's company, EBA Maschinenfabrik, manufactured the first cross-cut paper shredders in 1959 and continues to do so to this day as EBA Krug & Priester GmbH & Co. in Balingen.
Right before the fall of the Berlin Wall, a “wet shredder” was invented in the former German Democratic Republic. To prevent paper shredders in the Ministry for State Security (Stasi) from glutting, this device mashed paper snippets with water.
With a shift from paper to digital document production, modern industrial shredders can process non-paper media, such as credit cards and CDs, and destroy thousands of documents in under one minute. 
History of use.
Until the mid-1980s, it was rare for paper shredders to be used by non-government entities.
A high-profile example of their use was when the U.S. embassy in Iran used shredders to reduce paper pages to strips before the embassy was taken over in 1979, but some documents were reconstructed from the strips, as detailed below.
After Colonel Oliver North told Congress that he used a Schleicher cross-cut model to shred Iran-Contra documents, sales for that company increased nearly 20 percent in 1987.
Paper shredders became more popular among U.S. citizens with privacy concerns after the 1988 Supreme Court decision in "California v. Greenwood"; in which the Supreme Court of the United States held that the Fourth Amendment does not prohibit the warrantless search and seizure of garbage left for collection outside of a home. Anti-burning laws also resulted in increased demand for paper shredding.
More recently, concerns about identity theft have driven increased personal use, with the US Federal Trade Commission recommending that individuals shred financial documents before disposal.
Information privacy laws such as FACTA, HIPAA, and the Gramm–Leach–Bliley Act are driving shredder usage, as businesses and individuals take steps to securely dispose of confidential information.
Types.
Shredders range in size and price from small and inexpensive units designed for a certain amount of pages, to large units used by commercial shredding services that cost hundreds of thousands of dollars and can shred millions of documents per hour. While the very smallest shredders may be hand-cranked, most shredders are electrically powered.
Shredders over time have added features to improve the shredder user's experience. Many now reject paper that is fed over capacity to avoid jams; others have safety features to reduce risks. Some shredders designed for use in shared workspaces or department copy rooms have noise reduction.
Mobile shredding truck.
Larger organisation or shredding services sometimes use "mobile shredding trucks", typically constructed as a box truck with an industrial-size paper shredder mounted inside and space for storage of the shredded materials. Such a unit may also offer the shredding of CDs, DVDs, hard drives, credit cards, and uniforms, among other things.
Kiosks.
A "shredding kiosk" is an automated retail machine (or kiosk) that allows public access to a commercial or industrial-capacity paper shredder. This is an alternative solution to the use of a personal or business paper shredder, where the public can use a faster and more powerful shredder, paying for each shredding event rather than purchasing shredding equipment.
Services.
Some companies outsource their shredding to "shredding services". These companies either shred on-site, with mobile shredder trucks or have off-site shredding facilities. Documents that need to be destroyed are often placed in locked bins that are emptied periodically.
Shredding method, and output.
As well as size and capacity, shredders are classified according to the method they use; and the size and shape of the shreds they produce.
Security levels.
There are a number of standards covering the security levels of paper shredders, including:
Deutsches Institut für Normung (DIN).
The previous DIN 32757 standard has now been replaced with DIN 66399. This is complex, but can be summarized as below:
NSA/CSS.
The United States National Security Agency and Central Security Service produce "NSA/CSS Specification 02-01 for High Security Crosscut Paper Shredders". They provide a list of evaluated shredders.
ISO/IEC.
The International Organization for Standardization and the International Electrotechnical Commission produce "ISO/IEC 21964 Information technology — Destruction of data carriers". The General Data Protection Regulation (GDPR), which came into force in May, 2018, regulates the handling and processing of personal data. ISO/IEC 21964 and DIN 66399 support data protection in business processes.
Destruction of evidence.
There have been many instances where it is alleged that documents have been improperly or illegally destroyed by shredding, including:
Unshredding and forensics.
To achieve their purpose, it should not be possible to reassemble and read shredded documents. In practice the feasibility of this depends on
The resources put into reconstruction should depend on the importance of the document, e.g. whether it is
How easy reconstruction is will depend on:
Even without a full reconstruction, in some cases useful information can be obtained by forensic analysis of the paper, ink, and cutting method.
Forensic identification.
The individual shredder that was used to destroy a given document may be sometimes be of forensic interest. Shredders display certain device-specific characteristics, "fingerprints", like the exact spacing of the blades, the degree and pattern of their wear. By closely examining the shredded material, the minute variations of size of the paper strips and the microscopic marks on their edges may be able to be linked to a specific machine. (c.f. the forensic identification of typewriters.)
Recycling of waste.
The resulting shredded paper can be recycled in a number of ways, including: