Stands for “Digital Video Recorder.” A DVR is basically a VCR that uses a hard drive instead of video tapes. It can be used to record, save, and play back television programs. Unlike a VCR, however, a DVR can also pause live TV by recording the current show in real time. The user can choose to fast forward (often during commercials) to return to live television.
Most satellite and cable TV companies offer a DVR as an option with their digital television packages. Since cable boxes already provide program listings through some kind of TV guide interface, most DVRs allow users to use the guide to schedule recordings. For example, a user can use the remote to search through the guide’s program listings for the current week and select the shows he would like to record.
TiVo, the “brand name” DVR, performs the same functions as a DVR offered directly from a cable company. However, TiVo users can choose to buy the DVR box instead of renting it. Since TiVo is a standalone box, it does not require cable or satellite TV. While TiVo users who buy their own TiVo boxes may avoid the monthly rental fees, they must pay a monthly fee for program listings if they want to schedule recordings.
DVRs conveniently save shows in an list that the user can access at any time. Since the shows are stored on DVR’s hard drive, there is no need to rewind or fast forward to play a certain show, like a VCR requires. While DVRs make it even easier to record your favorite shows every week or even every day, it also makes it easier to watch more TV. And an excuse to watch more TV is something most of us don’t need.
Pharming is yet another way hackers attempt to manipulate users on the Internet. While phishing attempts to capture personal information by getting users to visit a fake website, pharming redirects users to false websites without them even knowing it.
While a typical website uses a domain name for its address, its actual location is determined by an IP address. When a user types a domain name into his or her Web browser’s address field and hits enter, the domain name is translated into an IP address via a DNS server. The Web browser then connects to the server at this IP address and loads the Web page data. After a user visits a certain website, the DNS entry for that site is often stored on the user’s computer in a DNS cache. This way, the computer does not have to keep accessing a DNS server whenever the user visits the website.
One way that pharming takes place is via an e-mail virus that “poisons” a user’s local DNS cache. It does this by modifying the DNS entries, or host files. For example, instead of having the IP address 22.214.171.124 direct to http://www.apple.com, it may direct to another website determined by the hacker. Pharmers can also poison entire DNS servers, which means any user that uses the affected DNS server will be redirected to the wrong website. Fortunately, most DNS servers have security features to protect them against such attacks. Still, they are not necessarily immune, since hackers continue to find ways to gain access to them.
While pharming is not as common as phishing scams are, it can affect many more people at once. This is especially true if a large DNS server is modified. So, if you visit a certain website and it appears to be significantly different than what you expected, you may be the victim of pharming. Restart your computer to reset your DNS entries, run an antivirus program, then try connecting to the website again. If the website still looks strange, contact your ISP and let them know their DNS server may have been pharmed.
Network Basic Input/Output System.” NetBIOS was introduced in 1983 by IBM as an improvement to the standard BIOS used by Windows-based computers. The BIOS provides an interface between the computer’s operating system and the hardware. As the name implies, NetBIOS adds support for networking, including the ability to recognize other devices connected to the network.
NetBIOS provides an API (Application Program Interface) for software developers to use. The NetBIOS API includes network-related functions and commands, which can be incorporated into software programs. For example, a programmer can use a prewritten NetBIOS function to enable a software program to access other devices on a network. This is much easier than writing the networking code from scratch. In other words, NetBIOS prevents programmers from having to “reinvent the wheel” just to get their program to connect to a network.
Ethics is a set of moral principles that govern the behavior of a group or individual. Therefore, computer ethics is set of moral principles that regulate the use of computers. Some common issues of computer ethics include intellectual property rights (such as copyrighted electronic content), privacy concerns, and how computers affect society.
For example, while it is easy to duplicate copyrighted electronic (or digital) content, computer ethics would suggest that it is wrong to do so without the author’s approval. And while it may be possible to access someone’s personal information on a computer system, computer ethics would advise that such an action is unethical.
As technology advances, computers continue to have a greater impact on society. Therefore, computer ethics promotes the discussion of how much influence computers should have in areas such as artificial intelligence and human communication. As the world of computers evolves, computer ethics continues to create ethical standards that address new issues raised by new technologies.
CSS Stands for “Cascading Style Sheet.” Cascading style sheets are used to format the layout of Web pages. They can be used to define text styles, table sizes, and other aspects of Web pages that previously could only be defined in a page’s HTML.
CSS helps Web developers create a uniform look across several pages of a Web site. Instead of defining the style of each table and each block of text within a page’s HTML, commonly used styles need to be defined only once in a CSS document. Once the style is defined in cascading style sheet, it can be used by any page that references the CSS file. Plus, CSS makes it easy to change styles across several pages at once. For example, a Web developer may want to increase the default text size from 10pt to 12pt for fifty pages of a Web site. If the pages all reference the same style sheet, the text size only needs to be changed on the style sheet and all the pages will show the larger text.
While CSS is great for creating text styles, it is helpful for formatting other aspects of Web page layout as well. For example, CSS can be used to define the cell padding of table cells, the style, thickness, and color of a table’s border, and the padding around images or other objects. CSS gives Web developers more exact control over how Web pages will look than HTML does. This is why most Web pages today incorporate cascading style sheets.
When you roll the cursor over a link on a Web page, it is often referred to as “hovering” over the link. This is somewhat like when your boss hovers over you at work, but not nearly as uncomfortable. In most cases, the cursor will change from a pointer to a small hand when it is hovering over a link. Web developers can also use cascading style sheets (CSS) to modify the color and style of link when a user hovers over it. For example, the link may become underlined or change color while the cursor is hovering over it.
The term hovering implies your computer screen is a three-dimensional space. In this conception, your cursor moves around on a layer above the text and images. When you click the mouse button while the cursor is hovering over a link, it presses down on the link to activate it. Hovering can also be used in a more general sense such as moving the cursor over icons, windows, or other objects on the screen.
Stands for “Wi-Fi Protected Access.” WPA is a security protocol designed to create secure wireless (Wi-Fi) networks. It is similar to the WEP protocol, but offers improvements in the way it handles security keys and the way users are authorized.
For an encrypted data transfer to work, both systems on the beginning and end of a data transfer must use the same encryption/decryption key. While WEP provides each authorized system with the same key, WPA uses the temporal key integrity protocol (TKIP), which dynamically changes the key that the systems use. This prevents intruders from creating their own encryption key to match the one used by the secure network.
WPA also implements something called the Extensible Authentication Protocol (EAP) for authorizing users. Instead of authorizing computers based soley on their MAC address, WPA can use several other methods to verify each computer’s identity. This makes it more difficult for unauthorized systems to gain access to the wireless network.
Stands for “Wired Equivalent Privacy.” WEP is a security protocol for Wi-Fi networks. Since wireless networks transmit data over radio waves, it is easy to intercept data or “eavesdrop” on wireless data transmissions. The goal of WEP is to make wireless networks as secure as wired networks, such as those connected by Ethernet cables.
The wired equivalent privacy protocol adds security to a wireless network by encrypting the data. If the data is intercepted, it will be unrecognizable to system that intercepted the data, since it is encrypted. However, authorized systems on the network will be able to recognize the data because they all use the same encryption algorithm. Systems on a WEP-secured network can typically be authorized by entering a network password.
A flat file database is a database that stores data in a plain text file. Each line of the text file holds one record, with fields separated by delimiters, such as commas or tabs. While it uses a simple structure, a flat file database cannot contain multiple tables like a relational database can. Fortunately, most database programs such as Microsoft Access and FileMaker Pro can import flat file databases and use them in a larger relational database.
Flat file is also a type of computer file system that stores all data in a single directory. There are no folders or paths used organize the data. While this is a simple way to store files, a flat file system becomes increasingly inefficient as more data is added. The original Macintosh computer used this kind of file system, creatively called the Macintosh File System (MFS). However, it was soon replaced by the more efficient Hierarchical File System (HFS) that was based on a directory structure.
While “frozen” describes the state of Minnesota from November to March, it also refers to an unresponsive computer. When a computer does not respond to any user input, it is said to be frozen. When a computer system freezes, or “locks up,” the screen stays the same and does not change no matter what buttons you press on your mouse or keyboard. You can tell if you computer has frozen if the cursor will not move when you move the mouse.
A computer typically freezes due to a software malfunction that causes the operating system to “hang.” This may happen because of many possible reasons, including a memory leak, an infinite calculation, or another reason. A computer can also freeze because of a hardware malfunction, such as a bad RAM chip or a processor error.
Since computers are not supposed to freeze, a software crash is often due to a software programming error or unrecognizable input. Fortunately, modern operating systems, such as Mac OS X are designed so that if one program crashes, it will not affect other programs and the computer will not freeze.
If your computer does freeze, you will need to restart the computer to make it function again. You can typically force your computer to shut down by holding the power button for several seconds. And remember – since most computer freezes happen unexpectedly, it is a good idea to save your work frequently!