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Stands for Digital Versatile Disc. A DVD is a type of optical media used for storing digital data. It is the same size as a CD, but has a larger storage capacity. Some DVDs are formatted specifically for video playback, while others may contain different types of data, such as software programs and computer files.
The original DVD-Video format was standardized in 1995 by consortium of electronics companies, including Sony, Panasonic, Toshiba, and Philips. It provided a number of improvements over analog VHS tapes, including higher quality video, widescreen aspect ratios, custom menus, and chapter markers, which allow you to jump to different sections within a video. DVDs can also be watched repeatedly without reducing the quality of the video and of course they dont need to be rewound. A standard video DVD can store 4.7 GB of data, which is enough to hold over 2 hours of video in 720p resolution, using MPEG-2 compression.
DVDs are also used to distribute software programs. Since some applications and other software (such as clip art collections) are too large to fit on a single 700 MB CD, DVDs provide a way to distribute large programs on a single disc. Writable DVDs also provide a way to store a large number of files and back up data. The writable DVD formats include DVD-R, DVD R, DVD-RW, DVD RW, and DVD-RAM. While the different writable DVD formats caused a lot of confusion and incompatibility issues in the early 2000s, most DVD drives now support all formats besides DVD-RAM.
A standard DVD can hold 4.7 GB of data, but variations of the original DVD format have greater capacities. For example, a dual-layer DVD (which has two layers of data on a single side of the disc) can store 8.5 GB of data. A dual-sided DVD can store 9.4 GB of data (4.7 x 2). A dual-layer, dual-sided DVD can store 17.1 GB of data. The larger capacity formats are not supported by most standalone DVD players, but they can be used with many computer-based DVD drives.
DVD in a Laptop DVD Drive

DNS records are stored in zone files and are used for translating domain names to IP addresses. They also contain other data, including the domain names name server and mail server information. If there are domain name aliases, such as the commonly used www preceding the domain name, these will also be listed in the DNS record.
A typical DNS record may look something like this:
;   Nameservers ;      IN   NS   ns1.4servers.com.   ; 123.456.789.01      IN   NS   ns2.4servers.com.   ; 123.456.789.02 ; ;   Domain Mail Handlers ; yourdomain.com.     IN   MX   0   mail yourdomain.com.     IN   MX  10   mail ; ; ;   hosts in order ; yourdomain.    IN   A   Your.IP.XXX www            IN   A   Your.IP.XXX smtp           IN   CNAME   www pop            IN   CNAME   www ftp            IN   CNAME   www mail           IN   A   Your.IP.XXX ; ; end
Since DNS records are made up entirely of text, they are easy to modify when needed. However, one small typo could redirect a domain name to the wrong Web server or prevent it from showing up at all. This is why it is important to enter DNS information accurately and double-check your changes entry before saving the zone file.

Unlike most computer terms, cyberspace does not have a standard, objective definition. Instead, it is used to describe the virtual world of computers. For example, an object in cyberspace refers to a block of data floating around a computer system or network. With the advent of the Internet, cyberspace now extends to the global network of computers. So, after sending an e-mail to your friend, you could say you sent the message to her through cyberspace. However, use this term sparingly, as it is a popular newbie term and is well overused.
The word cyberspace is credited to William Gibson, who used it in his book, Neuromancer, written in 1984. Gibson defines cyberspace as a consensual hallucination experienced daily by billions of legitimate operators, in every nation, by children being taught mathematical concepts... A graphical representation of data abstracted from the banks of every computer in the human system. Unthinkable complexity. Lines of light ranged in the non-space of the mind, clusters and constellations of data (New York: Berkley Publishing Group, 1989), pp. 128.

A Chromebook is a laptop that runs Googles Chrome OS operating system. While Google sells its own Chromebook model, the Chromebook Pixel, many other manufacturers offer Chromebooks as well. Examples include Dell, HP, Toshiba, Samsung, ASUS, and Acer.
Chromebooks are designed to be inexpensive and highly portable. They are considered thin clients since they have minimal internal storage. Unlike traditional laptops, Chromebooks are designed to run cloud-based applications and store data online. While the Chrome OS and some applications can run offline, Chromebooks work best when used with an Internet connection.
The Chrome OS includes several Google apps, such as the Chrome web browser, Gmail, Google , and YouTube applications. It also runs the Google Drive office suite and related apps such as Google Docs, Google Drawings, and Google Forms. Third party applications can be downloaded from the Chrome Web Store. Some Android apps can also run on Chrome OS via Googles App Runtime for Chrome (ARC).
Since Chromebooks do not run Windows or OS X, they do not natively support many traditional applications, such as Microsoft Office. However, you can run online versions of Word, Excel, and other common applications from the Chrome OS or through the Chrome web browser. These applications run on a remote server, but look and function like traditional desktop applications. Chromebooks also support remote access software, which allows you operate Windows or OS X computers from a Chromebook.

As most computer users know, some computing tasks can be tedious and repetitive. Fortunately, if a task is indeed repetitive, a batch process can be used to automate much of the work.
A batch process performs a list of commands in sequence. It be run by a computers operating system using a script or batch file, or may be executed within a program using a macro or internal scripting tool. For example, an accountant may create a script to open several financial programs at once, saving him the hassle of opening each program individually. This type of batch process would be executed by the operating system, such as Windows or the Mac OS. A Photoshop user, on the other hand, might use a batch process to modify several images at one time. For example, she might record an action within Photoshop that resizes and crops an image. Once the action has been recorded, she can batch process a folder of images, which will perform the action on all the images in the folder.
Batch processing can save time and energy by automating repetitive tasks. While it may take awhile to write the script or record the repetitive actions, doing it once is certainly better than having to do it many times.

Bash, though typically not capitalized, is an acronym for Bourne-Again Shell and is named after Stephen Bourne, the creator of the Unix shell sh. It is a command language interpreter derived from sh that can execute commands entered at a command prompt and process text file input.
Bash (bash) supports all the commands of the original Bourne shell (sh), as well as many others. It also includes features from the Korn shell (ksh) and C shell (csh), such as command line editing, command substitution syntax, and command history. Bash also supports brace expansion, which is used to generate related text strings. This operation provides an efficient way to search for filenames and rename multiple files. Newer versions of Bash support regular expressions (Bash 3.0) and associative arrays (Bash 4.0).
Bash was originally developed by Brian Fox for the GNU Project and was released in 1989. The bash shell was initially distributed with the GNU operating system and later became the default shell for multiple Linux distributions and Mac OS X. Recent versions of Bash (versions 3 and 4) were developed by Chet Ramey and are currently published by the Free Software Foundation, the same organization that distributes the GNU operating system.

802.11ac (also called 5G Wi-Fi) is the fifth generation of Wi-Fi technology, standardized by the IEEE. It is an evolution of the previous standard, 802.11n, that provides greater bandwidth and more simultaneous spatial streams. This allows 802.11ac devices to support data transfer rates that are several times faster than those of 802.11n devices.
Unlike previous Wi-Fi standards, which operated at a 2.4 GHz frequency, 802.11ac operates exclusively on a 5 GHz frequency band. This prevents interference with common 2.4 GHz devices, such as cordless phones, baby monitors, and older wireless routers. Computers and mobile devices that support 802.11ac will benefit from the 5 GHz bandwidth, but older wireless devices can still communicate with with an 802.11ac router at a slower speed.
The initial draft of the 802.11ac standard was approved in 2012, but 802.11ac hardware was not released until 2013. The initial 802.11ac standard (wave 1) supports a maximum data transfer rate of 1300 Mbps, or 1.3 Gbps, using 3 spatial streams. This is significantly faster than 802.11ns maximum speed of 450 Mbps. It also means 802.11ac is the first Wi-Fi standard that has the potential to be faster than Gigabit Ethernet. The second 802.11ac standard (wave 2) will support twice the bandwidth of wave 1 devices and offer data transfer rates of up to 3470 Mbps.

802.11a is an IEEE standard for transmitting data over a wireless network. It uses a 5 GHz frequency band and supports data transfer rates of 54 Mbps, or 6.75 megabytes per second.
The 802.11a standard was released in 1999, around the same time as 802.11b. While 802.11b only supported a data transfer rate of 11 Mbps, most routers and wireless cards at that time were manufactured using the 802.11b standard. Therefore, 802.11b remained more popular than 802.11a for several years. In 2003, the 802.11a standard was superseded by 802.11g, which uses the same 2.4 GHz band as 802.11a, but supports transfer rates of up to 54 Mbps.
NOTE: In order for a an 802.11a connection to take place, each device on the wireless network must support the 802.11a standard. For example, if a base station broadcasts an 802.11a signal, only computers with Wi-Fi cards that support 802.11a will be able to recognize the base station. While many routers are backwards compatible with older standards, it may be necessary to manually configure some routers to work with older 802.11a and 802.11b devices.

Encryption is the process of converting data to an unrecognizable or encrypted form. It is commonly used to protect sensitive information so that only authorized parties can view it. This includes files and storage devices, as well as data transferred over wireless networks and the Internet.
You can encrypt a file, folder, or an entire volume using a file encryption utility such as GnuPG or AxCrypt. Some file compression programs like Stuffit Deluxe and 7-Zip can also encrypt files. Even common programs like Adobe Acrobat and Intuit TurboTax allow you to save password-protected files, which are saved in an encrypted format.
Encryption is also used to secure data sent over wireless networks and the Internet. For example, many Wi-Fi networks are secured using WEP or the much stronger WPA encryption. You must enter a password (and sometimes a username) connect to a secure Wi-Fi network, but once you are connected, all the data sent between your device and the wireless router will be encrypted.
Many websites and other online services encrypt data transmissions using SSL. Any website that begins with https://, for example, uses the HTTPS protocol, which encrypts all data sent between the web server and your browser. SFTP, which is a secure version of FTP, encrypts all data transfers.
There are many different types of encryption algorithms, but some of the most common ones include AES (Advanced Encryption Standard), DES (Data Encryption Standard), Blowfish, RSA, and DSA (Digital Signature Algorithm). While most encryption methods are sufficient for securing your personal data, if security is extremely important, it is best to use a modern algorithm like AES with 256-bit encryption.
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