| Archived Data |
Is information that is not directly accessible to the computer user, but that the organisation maintains for long-term storage and record keeping purposes.
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| Backup |
Is a copy of a program or file to a second medium that is stored separately from the original as a precaution against the loss or damage of the original data.
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| Backup Data |
Is information that is not in use by an organisation and is regularly stored separately upon portable media enabling data recovery in the event of any losses.
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| Bit |
Acronym for binary digit, is the fundamental unit of digital information. A single bit can hold only one of two values: 0 or 1. The term was first used in 1946 by John Tukey, a leading statistician and adviser to five presidents. Combining 8 consecutive bits forms a byte and produces more meaningful information.
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| Byte |
Acronym for binary term, is a sequence of 8 bits forming a unit single unit of information. The byte is the basis for measurement of most computer data as multiples of the byte value. kilobytes (1,024 bytes), megabytes (1,048,576 bytes), and gigabytes (1,073,741,824 bytes).
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| Caching |
Is a technique of temporarily storing frequently accessed data in random access memory (RAM) or in a special area of a hard disk drive, to reduce the time required to read and write data.
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| Compression |
Is the reduction in size of a file, data is compressed into a form that minimizes the space required to store or transmit it. Data compression is also widely used in backup systems.
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| Computer Forensics |
Is the use of specialized techniques for recovery, authentication, and analysis of electronic data. Computer Forensics also includes the act of making digital data suitable for inclusion into a criminal/legal investigation.
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| DAT |
Acronym for Digital Audio Tape, Is used as a storage medium in some backup systems. A DAT cartridge is capable of holding up to 24 gigabytes of data.
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| Database |
A computer database is an electronic filing system. Traditional databases are organized by fields, records, and files. A field is a single piece of information; a record is a complete set of fields; and a file is a collection of records.
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| De-Duplication |
The identification of exact or near-duplicate files within a collection. This can greatly reduce the cost of working with electronic document, since multiple copies of the same file need not be processed.
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| Deleted Data |
Is data that was once ‘live’ and has been deleted by the computer system or user. Even after the data itself has been deleted, directory entries, pointers, or other metadata relating to the deleted data may remain on the computer.
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| Deletion |
Is the process whereby data is removed from ‘live’ files and other data storage structures on computers and rendered inaccessible except using specialist data recovery tools utilised within Computer Forensics.
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| Disk Array |
Is a linked group of one or more physical independent hard disk drives generally used to replace larger, single disk drive systems. A disk array may contain several disk drive trays, and is structured to improve speed and increase protection against loss of data.
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| Disk Mirroring |
A method of protecting data from hard disk failure. As each file is stored on the hard disk, a ‘mirror’ copy is made on a second hard disk or on a different part of the same disk.
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| Embedded File |
A file which is nested within another file.
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| Forensic Copy |
Is an accurate bit-for-bit reproduction of the information contained on an electronic device or associated media, including slack and unallocated space whose validity and integrity has been verified using an accepted algorithm.
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| GIF |
Acronym for Graphic Interchange Format. Pronounced jiff or giff (hard g), is a widely supported image-storage format promoted by CompuServe that gained early widespread use on online services and the Internet. Resolution is limited to 8-bits, or 256 colours and has built-in compression.
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| Gigabyte (GB) |
A gigabyte is a measure of computer data storage capacity and is equal to 1024 Megabytes or 1,073,741,824 bytes of information. |
| Hard Drive |
A storage medium located within a computer where a computer's operating system, applications, and data usually reside. Many disk drives improve their performance through a technique called caching.
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| HTML |
Acronym for HyperText Markup Language. Is a markup language designed for the creation of web pages and other information viewable in a browser. HTML is used to structure information denoting certain text as headings, paragraphs and lists and can be used to define the semantics of a document.
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| JPEG |
Acronym for Joint Photographic Experts Group. Is a commonly used standard method of compressing photographic images. JPEG is a lossy compression technique for colour images. Although it can reduce files sizes to about 5% of their normal size, some detail is lost in the compression.
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| Kilobyte (KB) |
Expression used to describe storage capacity or amount of data. One kilobyte is 1024 bytes/characters. Approximately equivalent to half a sheet of paper’s worth of typing, double-spaced.
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| Megabyte (MB) |
A Megabyte is a measure of computer data storage capacity and is a equal to 1 million bytes or 1,024 kilobytes or 1,048,576 bytes. The amount of computer memory needed to store 1,048,576 characters, which is approximately equal to one novel. Megabytes are used to describe the amount of memory on a hard disk or in random access memory.
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| Metadata |
Is a description or definition of electronic data, or data about data. Metadata describes how and when and by whom a particular set of data was collected, and how the data is formatted. Metatdata describes the content, quality, condition, history, and other characteristics of the data. Some, such as file dates and sizes, are easily visible; other metadata can be hidden or embedded and unavailable to computer users who are not technically proficient.
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| Mirroring |
Duplicating data onto another computer at another location. Mirroring is performed for backup purposes or to be in closer proximity to the user.
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| NSF File |
Is an email archive file for the Lotus Notes email system.
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| OCR |
Acronym for Optical Character Recognition refers to the process by which scanned images are electronically "read" to convert them into editable text. This conversion is performed after scanning, and may output formatted text or text-only files (flat ASCII files). Text generated by OCR is often input into text search databases, allowing retrieval of the original scanned image based on its content.
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| .OST |
Exchange Offiline File. Similar to a .PST file, it is an email archive generated by Microsoft Exchange.
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| PDF |
Acronym for Portable Document Format. A format from Adobe that enables a document to be distributed on different systems while preserving the original layout (.pdf).
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| Petabyte (PB) |
Is a measure of computer data storage capacity and is 2 to the 50th power (1,125,899,906,842,624) bytes. A petabyte is equal to 1,024 terabytes and is half of the content in all US academic research libraries.
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| Plaintext |
Is a message before encryption or after decryption, ie in its usual form which anyone or any system can read, as opposed to its encrypted form. It is the most portable format because it is supported by nearly every application on every machine. It is quite limited, however, because it cannot contain any formatting commands. Plain text is also called clear text.
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| .PST |
Is a Microsoft Outlook email archive file. If a Microsoft Exchange Server is used, the messages, calendar, and other items are delivered to and stored on the server. If an Exchange Server is not used, the messages, calendar, and other items are delivered to and stored locally in personal folders (.pst) files.
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| System File |
Files relating to the operating system and software applications enabling the software to be run. These files are not viewable but may contain limited amounts of Metadata.
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| Terabyte (TB) |
Is a measure of computer data storage capacity and is equal to 1,099,511,627,776 bytes, 1,048,576 megabytes, 1024 gigabytes and is equivalent to half of the content in an academic research library.
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| TIFF |
Acronym for Tagged Image File Format. Is a graphic file format developed by Aldus and Microsoft and is used to exchange files between applications and computer platforms. A TIFF is a flexible bitmap image format that is supported by virtually all graphic/image applications and is one of the most widely supported file formats for storing bit-mapped images.
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| USB Flash Drive |
A small, lightweight removable portable flash memory card that plugs into a computer’s USB port and functions as a portable hard drive with up to 16GB of storage capacity. USB flash drives are also known as "pen drives", "thumb drives", "flash drives", "USB keys".
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| XML |
Acronym forExtensible Markup Language, a specification developed by the W3C. Is a standard for creating mark-up languages which describe the structure of data. It allows designers to create their own customized tags, enabling the definition, transmission, validation, and interpretation of data between applications and between organizations.
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| X400 |
Was the original standard for e-mail addresses. Is an example of a standard that allows electronic messages to be sent from one computer to another regardless of hardware and software differences. It conforms to layer 7 of the OSI model and supports several types of transport mechanisms, including Ethernet, X.25, TCP/IP, and dial-up lines.
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| ZIP |
A popular data compression format and a means for compressing files so that they can be sent over the Net. Files that have been compressed with the ZIP format are called ZIP files and usually end with a.ZIP extension.
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