Glossary

Computer data is information processed or stored by a computer. This information may be in the form of text documents, images, audio clips, software programs, or other types of data. Computer data may be processed by the computer's CPU and is stored in files and folders on the computer's hard disk.

At its most rudimentary level, computer data is a bunch of ones and zeros, known as binary data. Because all computer data is in binary format, it can be created, processed, saved, and stored digitally. This allows data to be transferred from one computer to another using a network connection or various media devices. It also does not deteriorate over time or lose quality after being used multiple times.

A data type is a type of data. Of course, that is rather circular definition, and also not very helpful. Therefore, a better definition of a data type is a data storage format that can contain a specific type or range of values.

When computer programs store data in variables, each variable must be assigned a specific data type. Some common data types include integers, floating point numbers, characters, strings, and arrays. They may also be more specific types, such as dates, timestamps, boolean values, and varchar (variable character) formats.

Some programming languages require the programmer to define the data type of a variable before assigning it a value. Other languages can automatically assign a variable's data type when the initial data is entered into the variable. For example, if the variable "var1" is created with the value "1.25," the variable would be created as a floating point data type. If the variable is set to "Hello world!," the variable would be assigned a string data type. Most programming languages allow each variable to store a single data type. Therefore, if the variable's data type has already been set to an integer, assigning string data to the variable may cause the data to be converted to an integer format.

Data types are also used by database applications. The fields within a database often require a specific type of data to be input. For example, a company's record for an employee may use a string data type for the employee's first and last name. The employee's date of hire would be stored in a date format, while his or her salary may be stored as an integer. By keeping the data types uniform across multiple records, database applications can easily search, sort, and compare fields in different records.

Stands for "Double Data Rate." It is an advanced version of SDRAM, a type of computer memory. DDR-SDRAM, sometimes called "SDRAM II," can transfer data twice as fast as regular SDRAM chips. This is because DDR memory can send and receive signals twice per clock cycle. The efficient operation of DDR-SDRAM makes the memory great for notebook computers since it uses up less power.

Stands for "Double Data Rate 2." DDR2 RAM is an improved version of DDR memory that is faster and more efficient. Like standard DDR memory, DDR2 memory can send data on both the rising and falling edges of the processor's clock cycles. This nearly doubles the amount of work the RAM can do in a given amount of time. DDR and DDR2 are also both types of SDRAM, which allows them to run faster than conventional memory.

While DDR and DDR2 have many similarities, DDR2 RAM uses a different design than DDR memory. The improved design allows DDR2 RAM to run faster than standard DDR memory. The modified design also gives the RAM more bandwidth, which means more data can be passed through the RAM chip at one time. This increases the efficiency of the memory. Since DDR2 runs more efficiently than standard DDR memory, it actually uses less power than DDR memory, even though it runs faster. The only downside of DDR2 memory is that it is not compatible with standard DDR slots. So make sure your computer supports DDR2 RAM before upgrading your memory.

Stands for "Double Data Rate Type 3." DDR3 is an SDRAM specification introduced in 2007. Compared to previous DDR2 standard, DDR3 uses 30% less power and provides significantly faster data transfer speeds.

DDR3 memory modules are available in both DIMM and SO-DIMM form factors. DIMMs are commonly used for desktop PCs, while SO-DIMMs are typically used for laptops and all-in-one computers. While DDR3 DIMMs and SO-DIMM are the same size as their DDR2 counterparts, they are not compatible with DDR2 RAM slots. Fortunately, the connecting pins are arranged differently, so it is physical impossible to insert a DDR3 memory module into a a DDR2 RAM slot, and vice versa.

Several types of DDR3 memory exist, providing a range of maximum data transfer rates. The first version of DDR3 memory, called DDR3-800 (also "PC3-6400") provides peak transfer rates of of 6,400 MB/s. Other specifications include DDR3-1066, DDR3-1333, DDR3-1600, DDR3-1866, and DDR3-2133. DDR3-2133 (also called PC3-17000) supports peak transfer rates of 17,067 MB/s.

Computer programmers, like everybody else, are not perfect. This means the programs they write sometimes have small errors, called "bugs," in them. These bugs can be minor, such as not recognizing user input, or more serious, such as a memory leak that crashes the program. Before releasing their software to the public, programmers "debug" their programs, eliminating as many errors as possible. This debugging process often takes a long time, as fixing some errors may introduce others. Debugging your windshield at a gas station is much easier than debugging a computer program.

This term is used to describe a preset value for some option in a computer program. It is the value used when a setting has not been specified by the user. For example, the default font setting in Netscape Communicator is "Times." If you don't go to the Netscape preferences and change it to something else, the "Times" font will be used -- by default. Typically, default settings are set to what most people would choose anyway, so there's often no reason to change them. However, if you're one of those people who has to customize everything that you possibly can, then you can go ahead and change all the default settings you want.

"Default" can also be used as a verb. If a custom setting won't work for some reason, the program will "default" to the default setting. For example, say you're working on computer that is on a network and you print something when there is no printer specified. If you're lucky and don't get some nasty error message, the print job will default to the default printer and your work will be printed.

Your computer's desktop is much like a physical desktop. You probably keep a number of commonly used items on your desk such as pens, papers, folders, and other items. Your computer's desktop serves the same purpose -- to give you easy access to items on your hard drive. It is common to store frequently used files, folders, and programs on your desktop. This allows you to access the items quickly instead of digging through the directories on your hard drive each time you want to open them.

Both the Macintosh and Windows interfaces use the desktop as a central part of the interface. Both operating systems allow you to move items on and off the desktop as you wish and offer organization tools to arrange and clean up the items on the desktop. Yes, it would be nice if there was an option like that for a real-life desktop. You can also customize your computer's desktop with the pattern or background image of your choice. For more information on customizing your desktop, view this Help Center article.

As the name implies, a dialog box serves to initiate a dialog with the user. It is a window that pops up on the screen with options that the user can select. After the selections have been made, the user can typically click "OK" to enter the changes or "Cancel" to discard the selections. It is customary for menu options that include an ellipsis at the end, such as "Preferences..." or "Save As...", to open a dialog box when selected.

For example, if a user selects "Internet Options..." from the Options menu in Internet Explorer, a dialog box will pop up allowing the user to choose the default home page, change the security settings, empty the browser cache, and modify several other settings. Once the selections have been made, the user can click "OK" to use the new settings, or "Cancel" to discard the changes. Some Windows programs also have an "Apply" option that activates the selections without closing the dialog box.

When a user selects "Open..." from the File menu, an "Open dialog box" appears, allowing the user to browse the hard drive and other disks for files to open. When "Save As..." is chosen from the File menu, a "Close dialog box" pops up, allowing the user to type the name of the file and choose where to save it. While dialog boxes may not seem too exciting, they provide an intuitive way to communicate with the computer and are an essential part of today's computer interfaces.

Digital information is stored using a series of ones and zeros. Computers are digital machines because they can only read information as on or off -- 1 or 0. This method of computation, also known as the binary system, may seem rather simplistic, but can be used to represent incredible amounts of data. CDs and DVDs can be used to store and play back high-quality sound and video even though they consist entirely of ones and zeros.

Unlike computers, humans perceive information in analog. We capture auditory and visual signals as a continuous stream. Digital devices, on the other hand, estimate this information using ones and zeros. The rate of this estimation, called the "sampling rate," combined with how much information is included in each sample (the bit depth), determines how accurate the digital estimation is.

For example, a typical CD audio track is sampled at 44.1 KHz (44,100 samples per second) with a bit depth of 16 bits. This provides a high-quality estimation of an analog audio signal that sounds realistic the human ear. However, a higher-quality audio format, such as a DVD-Audio disc, may be sampled at 96 KHz and have a bit depth of 24 bits. The same song played on both discs will sound more smooth and dynamic on the DVD-Audio disc.