C
A general-purpose programming language closely associated with the UNIX operating system.

C++
An industry standard object-oriented compiled language, formally standardized in 1998, but tracing its history to the early 1980s, with an heritage in C and Simula. C++ is a general-purpose programming language with a bias towards systems programming. C++ runs on most computers from the most powerful supercomputers to the ubiquitous personal computers.

CA - Certificate Authority
A Certificate Authority (CA) is a third party which verifies the identity of merchants and their sites. The certificate authority issues a certificate (also called a digital certificate or an authentication certificate) to an applicant company, which can then put the certificate up on its site.

Cable Modem
A special type of modem that connects to a local cable TV line to provide a continuous connection to the Internet. Like an analog modem, a cable modem is used to send and receive data, but the difference is that transfer speeds are much faster. A 56 Kbps modem can receive data at about 53 Kbps, while a cable modem can achieve about 1.5 Mbps (about 30 times faster). Cable modems attach to a 10Base-T Ethernet card inside your computer.

Cache
A section of a computer's memory which retains recently accessed data in order to speed up repeated access to the same data. Your computer and browser use cache memory to load Web pages more quickly. Your ISP also uses a cache for this purpose. If you ask your computer to view a page, and it finds the page in the cache, it will read the cached page instead of the page from the Internet, unless you reload the page.

Canonical Name
Characteristic of adhering to standard, accepted, or authoritative procedures or principles. Conforming to the general rules for encoding - that is, not compressed, compacted, or in any other form specified by a higher protocol.

Catch all
An email address that "catches" all emails that are misdirected or sent to non-existent accounts. Usually a forwarding email address can be associated to send this mail to a specified address.

CDF - Channel Definition Format
An XML-based data format used in Microsoft® Internet Explorer 4.0 and later to describe Active Channel™ content and desktop components. CDF permits a Web publisher to offer frequently updated collections of information, or channels, enabling automatic delivery to compatible Web clients. The user only needs to choose the channel once, and scheduled deliveries of the channel information will be delivered to the client without further intervention.

CERN
The European Laboratory for Particle Physics located in Geneva, Switzerland. The World Wide Web originated in this laboratory in 1989 when its staff proposed a multimedia, hyperlinked system of documents. This laboratory has sometimes been referred to as the "home of the Web." The NCSA staff developed the first graphical browser, Mosaic, for the World Wide Web. Mosaic was released (free) for public use in 1990.

Certificate
A digital certificate is an electronic document which links a public key to a person or a company in a public key infrastructure enabling the user(s) to send encrypted and digitally signed electronic messages. The certificate identifies the user and is required to verify his digital signature. The certificate contains information about the identity and public key of the person/company as well as the certificate's expiration date. Furthermore, the certificate may contain information about the usage of the certificate. Each certificate is signed with the private key of the CA. It vouches for an individual or organisational identity. A digital certificate can be compared to a driver's license or an ID card in that it authorises the bearer to conduct certain operations, hence making it possible to secure e-business activities.

CFM
An extension used for Cold Fusion file types for use on the web.

CGI - Common Gateway Interface
Short for Common Gateway Interface, a small script that processes data taken from the user (such as from a form application). A few common CGI scripts are form emails, hit counters, calendars, clocks, Bulletin Board systems, ane more.

Cgi-bin
The common directory on an internet Web server where all CGI scripts are stored for use.

CHAP - Challenge Handshake Authentication Protocol
Is a security feature supported on lines using PPP encapsulation that prevents unauthorised access , CHAP does not itself prevent unauthorised access , it merely identifies the remote end, though is a more secure procedure for connecting to a system than PAP. The router or access server then determines whether that user is permitted access.

Chat Server
Allows you to develop a chat room or other type of chat service for your web site visitors. Be sure to check with the web host company about the details of the chat services offered. Some servers permit you to configure the service, and others pre-configure everything for you while others do not allow chat rooms at all.

CHMOD
UNIX command for changing permissions Each file is assigned permissions based upon the ownership, the group membership, and the accessibility of the file to non-authenticated users. Permissions are assigned in a combination of three variants: Read permission (assigned a numeric value of 4) allows a user to view the contents of a file or a directory. Write permission (assigned a numeric value of 2) allows a user to view and make changes to a file. Execute permission (assigned a numeric value of 1) allows a user to run the program contained in a file. Only the owner of the file or directory can change permissions UNIX clients can modify permissions through an F.T.P. client, such as CuteFTP or WS-FTP.

CIDR - Classless InterDomain Routing
Technique supported by BGP4 and based on route aggregation. CIDR allows routers to group routes together in order to cut down on the quantity of routing information carried by the core routers. With CIDR, several IP networks appear to networks outside the group as a single, larger entity. With CIDR, IP addresses and their subnet masks are written as 4 octets, separated by periods, followed by a forward slash and a 2-digit number that represents the subnet mask.

Class A Subnet
Traditionally subnets have been broken down into three size classes based on the 4 octets that make up an IP address. For example: 123.001.002.178. Class A was any subnet that shared the first octet. Apple for example has a class A subnet. The first octet was 0017. All IP addresses starting with 17 are controlled by Apple. A class A subnet has over 16 Million possible IP addresses. Apple thus effectively controls 1/255th of the Internet.

Class A Subnet
Traditionally subnets have been broken down into three size classes based on the 4 octets that make up an IP address. For example: 123.001.002.178. Class A was any subnet that shared the first octet. Apple for example has a class A subnet. The first octet was 0017. All IP addresses starting with 17 are controlled by Apple. A class A subnet has over 16 Million possible IP addresses. Apple thus effectively controls 1/255th of the Internet.

Classless Subnet Delegation
Classless subnets are delegated in the reverse zone of the parent that is delegating. The key tools for the delegation are PTR records, NS records and CNAME records. The NS records declares the existence of the subnet’s domain name servers. The PTR records attach canonical names to reverse lookup addresses. CNAME records can be used to create aliases for simplification.

CLI - Command Line Interface
A method of controlling the computer by typing commands. The user must generally memorize specific commands. Older machines still use them because GUI systems require too much overhead. Some people prefer command lines, because it is faster to type one or two commands than to manipulate an image on the screen.

Click Through
The process of clicking on a link in a search engine output page to visit an indexed site. This is an important link in the process of receiving visitors to a site via search engines. Good ranking may be useless if visitors do not click on the link which leads to the indexed site. The secret here is to provide a good descriptive title and an accurate and interesting description.

Client
A software program that is used to contact and obtain data from a Server software program on another computer, often across a great distance. EachClient program is designed to work with one or more specific kinds of Server programs, and each Server requires a specific kind of Client. A Web Browser is a specific kind of Client.

Client / Server
Client/server describes the relationship between two computer programs in which one program, the client, makes a service request from another program, the server, which fulfills the request. In a network, computer transactions using the client/server model are very common. In the usual client/server model, one server, sometimes called a daemon, is activated and awaits client requests. Typically, multiple client programs share the services of a common server program. Both client programs and server programs are often part of a larger program or application. Relative to the Internet, your Web browser is a client program that requests services from a Web server in another computer somewhere on the Internet.

Cloaking
The process by which your site can display different pages under different circumstances. Primarily used to show optimized page to the search engines and a different page to humans. Most search engines will penalize a site if they discover that it is using cloaking.

Clustering
Connecting many computers and making them appear as one machine. This is done to increase reliability and performance. A server architecture that emulates multiprocessing by interconnecting two or more individual computers in order to share the application processing load. Microsoft's future clustering technology for Windows NT now carries the code name Wolfpack. A number of third parties offer proprietary clustering hardware and software for Windows NT Server 4.0.

CMS - Content Management System
A system used to manage the content of a Web site. Can allow a content manager or author, who may not know Hypertext Markup Language (HTML), to manage the creation, modification, and removal of content from a Web site without needing the expertise of a Webmaster.

CNAME Record
A DNS Canonical Name resource record used for nicknames or aliases. The name associated with the resource record is the nickname. The data portion is the official or canonical name.

Cold Fusion
ColdFusion is a programming language based on standard HTML that is used to write dynamic webpages. ColdFusion enables you to incorporate live data into dynamically created web pages. For example, with ColdFusion your online store can actually deal with real-time inventory levels, enabling you to notify your customers of any out of stock items. ColdFusion Web applications can contain XML, HTML, and other client technologies such as CSS and JavaScript.

Colocation Server Hosting
Allows you to retain full management responsibility for day-to-day hosting, while enjoying access to security-enhanced, reliable data centres and high-bandwidth Internet connectivity. In colocation, customers typically select and manage their own Web servers, including the hardware and software costs; up-front hardware investment; vendor provides 24x7 data centre with redundant power and security management; vendor provides high-speed Internet connection and services in an elemental fashion.

Comment Tags
This HTML tag is used to insert comments that won't be viewed by users into your pages. Some search engines read comment tags, which can include keyword text and descriptions. Comment tags are also used to hide javascript code from non-compliant browsers.

Control Panel
A Web-based Control Panel is a web hosting admin tool that allows you to set mail forwarding options, enable/disable anonymous FTP access, view statistics, change passwords and more. Users may also update account contact information at anytime without having to contact customer support.

Cookie
A cookie is a little piece of information handed to a WWW client by a WWW server that contains information that can be retrieved by the server later. For instance, a server can hand your browser a cookie when you fill out a form stating your preferences for visiting that server. Then, the next time you visit the site, the server can read your preferences from the cookie it put in your browser on the first visit, and customize the appearance of the web site to your preferences. A cookie can also be called a Persistent Client Side State Object.

cPanel
cPanel is designed for the end users of a hosting system and allows them to control everything from adding / removing email accounts to administering MySQL databases.

CPU - Central Processing Unit
Refers either to the principle microchip that the computer is built around (such as the Pentium or PowerPC chip) or the box that houses the main components of the computer.

Crawler
A crawler is much like a spider except it is programmed to constantly surf the web, following any and all links it comes across. As it visits new websites, it checks its own database to see if the site is listed. If the site is already listed, it makes note of any changes and calculates a search engine ranking for the site. If the site has not been previously listed, the crawler will record all important information, add the website to the database, and assign a ranking to it.

Cronjobs
Cron is the ability to run programs based on the system clock of a web server. This can be useful for automating simple processes like backing up data.

CSS - Cascading Style Sheets
Cascading Style Sheets, a W3C Recommendation. Stylesheets when attached to documents describe how the document is displayed or printed, e.g. a CSS sheet is attached to an HTML document, to influence its layout when accessed via a browser. CSS supports cascading, i.e. a single document may use two or more stylesheets that are than applied according to specified priorities (=cascade).

Custom Design
A web site or site design that is specially made to a clients specifications, regarding finish, size, color or function. Custom items typically have a longer lead time and are usually not returnable. On the flip side a custom design is very difficult to copy, making your web site unique.

Cyber Squatting
Term used when someone purchases a domain name for the specific purpose of extorting money from that person/business who wants to use the domain name legitimately.