Data storage is the recording (storing) of information (data) in a storage medium. Recording is accomplished by virtually any form of energy. DNA and RNA, handwriting, phonographic recording, magnetic tape, and optical discs are all examples of storage media. Electronic data storage requires electrical power to store and retrieve data. Data storage in a digital, machine-readable medium is sometimes called digital data. Computer data storage is one of the core functions of a general purpose computer. Electronic documents can be stored in a much less space than paper documents.Barcodes and magnetic ink character recognition (MICR) are two ways of recording machine-readable data on paper.
A recording medium is a physical material that holds information. Newly created information is distributed and can be stored in four storage media, print, film, magnetic, and optical and seen or heard in four information flows, telephone, radio and TV, and the Internet as well as being observed directly. Digital information is stored on electronic media in many different recording formats.
With electronic media, the data and the recording media are sometimes referred to as "software" despite the more common use of the word to describe computer software. With (traditional art) static media, art materials such as crayons may be considered both equipment and medium as the wax, charcoal or chalk material from the equipment becomes part of the surface of the medium.
Some recording media may be temporary either by design or by nature. Volatile organic compounds may be used to preserve the environment or to purposely make data expire over time. Data such as smoke signals or skywriting are temporary by nature. Depending on the volatility, a gas (e.g. atmosphere, smoke) or a liquid surface such as a lake would be considered a temporary recording medium if at all.
A 2003 UC Berkeley report estimated that in 2002 about 5 exabytes of new information was produced with 92 percent being stored on hard disk drives; this represents a doubling since 2000. The new information flow in 2002 was almost 18 exabytes, three and a half times more than was recorded with ninety eight percent of this information sent and received in telephone calls. The report noted that the storage of new information has been growing at a rate of over 30% a year (upper estimate, uncompressed) with dramatic growth in storage of new information since 2000 in every storage medium except film.
It is estimated that the year 2002 marked the beginning of the digital age for information storage, which means that this years marked the date where human kind started to store more information on digital, than on analog storage devices. In the year 1986, merely 1% of the world's capacity to store information was in digital format, which grew to 3% by 1993, 25% in the year 2000, and exploded to 97% of the world's storage capacity by 2007.
In a 2007 study in Science, it was estimated that the world's technological capacity to store information in analog and digital devices grew from less than 3 (optimally compressed) exabytes in 1986, to 295 (optimally compressed) exabytes in 2007, doubling roughly every 3 years.
In a less comprehensive study, the International Data Corporation estimated that the total amount of digital data was 281 exabytes in 2007, and had for the first time exceeded the amount of storage.
A study published in 2011 estimated that the world's technological capacity to store information in analog and digital devices grew from less than three (optimally compressed) exabytes in 1986, to 295 (optimally compressed) exabytes in 2007, and doubles roughly every three years.