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  • Cache
    Caches come in many types, but they all work the same way: They store information where you can get to it quickly. A Web browser cache stores the pages, graphics, sounds, and URL's of online places you visit on your hard drive. That way, when you go back to the page, everything doesn't have to be downloaded all over again. This speeds things up.
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  • Canonical name (CNAME)
    A host's official name as opposed to an alias. The official name is the first hostname listed for its Internet address in the hostname database. A host with multiple network interfaces may have more than one Internet address, each with its own canonical name and zero or more aliases.
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  • Card absent
    A payment card transaction in which the buyer's card is not physically presented to the merchant. For example, the cardholder may order goods over the phone from a merchant who obtains the payment card number and expiration date verbally. For Web-based commerce, the commerce service provider typically captures the card information for the merchant.
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  • Card present
    A payment card transaction in which the buyer's card is physically presented to the merchant, for example, in a retail store.
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  • Card reader
    A device that reads information from the magnetic stripe on a payment card, or the contact pad on a smart card.
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  • CC
    Courtesy Copy, derived from the non-digital Carbon Copy. A way to send an e-mail message to a person other than the main recipient or recipients. The CC'ed party can see that they are not the main recipient of the letter.
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  • CD-ROM
    Compact Disc-Read Only Memory: This is the same disc as the audio compact disc except that it contains optical information, instead of audio information.
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  • CERN
    Conseil European pour la Recherche Nucleaire. CERN is a large physics particle-accelerator laboratory located in Geneva on the French-Swiss border, and was the original birthplace of the World Wide Web (WWW) as a result of the work of Tim Berners-Lee. Also used as colloquial term for the particular Web server produced there.
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  • Certificate
    A digital document attesting to the binding of a public key to a person, company, machine, or other entity. In its simplest form, a certificate contains a public key, the name of its possessor, and a digital signature using the private key of a certifying authority (CA). The CA guarantees that the person or entity named is in fact the legitimate holder of the public key. A certificate also commonly contains the expiration date of the key, the name of the CA that issued the certificate, the serial number of the certificate, and other related information. Certificates are meant as a way around the problem that public keys are intentionally publicly accessible, which makes it possible for any published public key to be claimed by anyone, including entities to whom (or which) it does not belong. A certificate is a hint, albeit a strong one, that the holder is who they say they are. The final confirmation is an exchange of messages proving that the public key in the certificate matches the private key in the sending entity's possession.
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  • Certificate Revocation List (CRL)
    A list of certificates that have been revoked before their scheduled expiration date.
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  • Certificate Signing Unit (CSU)
    A tamperproof storage mechanism used by a certifying authority (CA) to store private keys.
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  • Certifying Authority (CA)
    An organization that issues certificates and provides assurance of an entity's identity. A certifying authority is an entity that is well known and trusted and whose public key is well known. A CA cantransfer that trustworthiness to less well-known persons or entities by verifying to its satisfaction that a given public key really does belong to that entity, and then creating a certificate for it, digitally signed with the CA's private key. The public key, thus certified, can then be trusted for purposes of privacy or authentication, so long as the entities can obtain the CA's public key and demonstrate that corresponding private keys are also in hand.
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  • Certification Authority (CA)
    An official who is trusted by certificate users to issue digital certificates and vouch for the binding between the data items in certificates, particularly certificates that bind an identity to a public key.
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  • CGI (Common Gateway Interface)
    A specification of how a Web server can communicate with a program (script or binary) in a way that provides complete isolation of the server from the program, for the safety of the server. Often such programs are referred to as CGI scripts. When a Web client accesses a URL that points to a CGI script, the HTTP server specified in the URL executes the program, passing to it any data provided by the client in a query string. The output of the CGI script is then returned to the originating client by the HTTP server specified in the original URL.
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  • Charge card
    A payment card for which the cardholder is billed without credit terms; the bill must be paid in full each billing period, typically 30 calendar days. An example is the American Express card. Contrast with credit card and debit card.
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  • Chat
    Talking on the Internet in real time, generally by typing messages to a group of people, or private messages to a specific user. "Chat rooms" are groups of people that chat about a specific topic, generally by pointing their chat client at a specific chat server.
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  • Cipher
    An algorithm for reversible transformation of data.
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  • Ciphertext
    Text that has undergone encryption.
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  • Classless Interdomain Routing (CIDR)
    A protocol used by ISPs and other large networks on the Internet to group large blocks of networks under fewer network addresses. If it weren't for CIDR, the number of network addresses on the Internet would already have far exceeded the storage capacity of even the most powerful routers.
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  • Client
    A computer or software application that uses the services of another computer or server.
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  • Client/Server
    A term denoting the technology relationship between two types of computers, the client (normally an individual's computer) and the server (a computer that stores and delivers information to individual users).
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  • Clinical trial recruiting
    The processes and outreach activities used to identify, contact, and enroll appropriate candidates in clinical trials to assess the efficacy of new drugs, medical devices, or procedures.
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  • Collocated hosting
    A form of Web hosting where the customer brings their own equipment into the Web Hosting provider's data center. By collocating their equipment in this fashion, they can take advantage of the provider's abundant bandwidth, as well as other value-added services.
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  • COM port
    A contraction of communications used to describe the serial port on a PC. COM is usually used in conjunction with a number, as in COM1, COM2, COM3, or COM4.
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  • Commerce Service Provider (CSP)
    Supplies the system and services to establish the back-office infrastructure for businesses. Major aspects include: the processing of secure transactions, the developing and managing of customer relationships, the collecting of payment, and the delivering of products or services over the Web. A CSP may provide the following services: buyer authentication, order taking, details of what is for sale in an electronic offer, validation, payment processing (via traditional credit card payment processors), and generation of electronic receipts. Fulfillment may be made of electronic goods or physical goods. See also electronic commerce.
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  • Community of Interest
    An affinity group, or group that shares similar interests, brought together online through chat, discussion groups, and document sharing, for the purposes of collaboration and information and knowledge exchange.
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  • Comparative Effectiveness
    The analysis of how various procedures, treatments, drugs or interventions compare with one another using data, advanced technology and analytics to conduct comparison studies of two or more therapies.
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  • Computer Emergency Response Team (CERT)
    An organization that studies computer and network security to provide incident response services to victims of attack and publish alerts concerning vulnerabilities and threats. For example, the CERT at Carnegie-Mellon University.
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  • Constrained speech recognition program
    A speech recognition program that limits the available vocabulary.
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  • Content
    The information contained in a Web site, including the structure in which it is presented.
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  • Content provider
    A company, organization, individual, or other entity that makes Web content available on a content server. See also Internet service provider.
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  • Content server
    A Web server that provides Web content. See also front-office server.
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  • Content tree
    All the content available under a content root.
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  • Continuous-Speech Recognition
    The ability of a speech recognition program to understand speech spoken without pauses between the words. A voice input system in which the speaker may use normal conversational flow.
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  • Control key (CTRL)
    A key used to access commands through the computer keyboard rather than the menus. CTRL commands are commonly shortcuts.
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  • Control panel
    A computer window that allows users to adjust various aspects of the indivdual computer, such as the volume, fonts, desktop background, mouse speed, and clock.
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  • Cookie
    A small amount of information stored on a client computer by a Web site that is sent back to the site each time the user visits it. The use of cookies to maintain persistent, client-side state information significantly extends the capabilities of Web-based client/server applications.
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  • CNAME
    Short form of canonical name.
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  • CPU
    Central Processing Unit. This is the most powerful microprocessor chip in your computer. Sometimes the term CPU is used to describe the whole box that contains the chip (along with the motherboard, expansion cards, disk drives, power supply, and so on).
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  • Credit
    A transaction that credits a buyer's account, usually as the result of the buyer returning a good that was purchased.
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  • Credit card
    A payment card used to make purchases and/or to obtain cash. The amount of a credit card purchase or withdrawal is billed to the cardholder periodically (usually monthly) on a statement that aggregates that period's transactions, whereas it is credited immediately to the merchant. Contrast with debit card and charge card.
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  • Credit card payment process
    The three-step process that a merchant (or commerce service provider acting on behalf of a merchant) must complete in order to accept credit card payments. This process relies on a credit card processor from whom the merchant obtained a merchant ID. The three steps include: authorization, verification of fulfillment, and settlement.

    1)Authorization

    The merchant transmits to its credit card processor the buyer's credit card type and number, expiration date, the seller's merchant ID, and the amount to be paid. The credit card processor responds by confirming or denying that the amount can be charged to that credit card number. If the response is negative, then authorization is not granted and the purchase cannot occur. If the response is positive, then the amount is reserved on the credit card account for a fixed period. The merchant is given an identifier of the transaction, o be used later for settlement.

    2) Verification of fulfillment (if credit transaction response was positive)

    Either deliver the product being purchased, Or notify the entity responsible for fulfillment of the order, then wait for confirmation or cancellation of order shipment from that entity.

    3)Settlement (only if fulfillment has occurred)

    The merchant transmits to the credit card processor the identifier of the fulfilled transaction for payment is now due. The credit card processor instructs the issuing bank to debit the cardholder's account. The credit card processor instructs the acquiring bank to credit the merchant's account. The credit usually becomes visible to the merchant after approximately three days.
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  • Credit card processor
    A company that performs authorization and settlement of credit card payments, usually handling several types of credit and payment cards (such as Visa, MasterCard, and American Express). If merchants wish to sell their products to cardholders, they retain the services of one or more processors who handle the credit cards that the merchant wishes to accept. When a merchant retains the services of a credit card processor, it is issued a merchant ID.
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  • CSU
    Also see Certificate Signing Unit (CSU). Channel Service Unit. Provides digital interface between end-user equipment and telephone lines. Connects DSU to telephone company circuit. Provides phone company with loopback testing and circuit protection from power surges originating in customer equipment.
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  • Cyber-
    The prefix cyber- is most often used to make whatever word it's attached to seem hip, cool, and connected in some loose way to the world of computers or the Internet.
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  • Cyberspace
    A word used loosely to refer to virtual reality, the Internet, the World Wide Web, and many other kinds of computer systems in which users may become immersed.
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