INTERNET TERMS

Captcha

A captcha is program used to verify that a human, rather than a computer, is entering data. Captchas are commonly seen at the end of online forms and ask the user to enter text from a distorted image. The text in the image may be wavy, have lines through it, or may be highly irregular, making it nearly impossible for an automated program to recognize it. (Of course, some captchas are so distorted that they can be difficult for humans to recognize as well.) Fortunately, most captchas allow the user to regenerate the image if the text is too difficult to read. Some even include an auditory pronunciation feature.

By requiring a captcha response, webmasters can prevent automated programs, or "bots," from filling out forms online. This prevents spam from being sent through website forms and ensures that wikis, such as Wikipedia, are only edited by humans. Captchas are also used by websites such as Ticketmaster.com to make sure users don't bog down the server with repeated requests. While captchas may be a minor inconvenience to the user, they can save webmasters a lot of hassle by fending off automated programs.

The name "captcha" comes from the word "capture," since it captures human responses. It may also be written "CAPTCHA," which is an acronym for "Completely Automated Public Turing test to tell Computers and Humans Apart."

Cc

Stands for "Carbon Copy." The term comes from carbon copying, in which a piece of carbon paper copies writing from one paper to another (often used when filling out forms). However, the term is now commonly used in reference to e-mail. When you send an e-mail message, you typically type the recipient's address in the "To:" field. If you want to send the message to one or more other recipients, you can use the "Cc:" field to add additional addresses. This will send the e-mail to the address in the "To:" field and to each address listed in the "Cc:" field as well.

The "Cc:" option is often used in business communications when a message is intended for one person, but is relevant to other people as well. For example, a retail employee may e-mail another employee saying he can work for her on a certain day. He might include his manager's and assistant manager's e-mail addresses in the "Cc:" field to let them know he is taking the work shift. Similarly, a team member working on a product design may e-mail his boss with the latest design revisions and may "Cc:" the other members of his team to let them know the e-mail has been sent.

"CCing" (yes, it can also be used as a verb) is a quick way to let other people in on your e-mail communications. It is efficient because you don't have to send separate messages to each individual address. However, remember that When you Cc an e-mail, all the recipients can see the other addresses the message was sent to. If you want to hide the additional addresses, use Blind Carbon Copy (Bcc) instead.

CDN

Stands for "Content Delivery Network." A CDN is a group of servers distributed in different locations. Small CDNs may be located within a single country, while large CDNs are spread across data centers around the world.

CDNs are used to provide content to users in different locations as quickly as possible. For example, a user in San Francisco may receive website content from a server in Los Angeles, while a user in England may receive the same content from a server in London. This is accomplished using data replication, which stores the same data on multiple servers. Whenever you access a website hosted on a CDN, the network will intelligently provide you with the content using the server closest to the your geographical location.

By providing Internet-based content over a CDN, large businesses can avoid bottlenecks associated with serving data from a single location. It also helps limit the impact of security breaches, such as denial of service attacks. If hardware fails on one server, the CDN can quickly reroute traffic to the next best server, limiting or even eliminating downtime.

While CDNs are often used to host websites, they are commonly used to provide other types of downloadable data as well. Examples include software programs, images, videos, and streaming media. Cloud computing services are often provided over content delivery networks as well. Since CDNs automatically choose the best server for each user, there is no need to manually choose the most efficient location, like some FTP download services require.

NOTE: While CDNs are often accessed via standard URLs, many CDNs include the letters "cdn" in their web address.

Certificate

An SSL certificate, or secure certificate, is a file installed on a secure Web server that identifies a website. This digital certificate establishes the identity and authenticity of the company or merchant so that online shoppers can trust that the website is secure and reliable. In order to verify that these sites are legitimate (they are who they say they are), the companies and their websites are verified by a third party, such as Verisign or Thawte.

Once the verification company establishes the legitimacy of an organization and the associated website, they will issue an SSL certificate (for the small fee of a few hundred dollars). This digital certificate is installed on the Web server and will be viewable when a user enters a secure area of the website. You can tell you are visiting a secure page when the URL starts with "https." To view the certificate, click the lock icon near one of the edges of your browser window.

Because digital certificates verify a company's current status, they do not last forever. SSL certificates typically expire every one to three years. If the certificate is not renewed in time, you may see an alert box pop up that says "This website's certificate has expired." This error has nothing to do with you or your computer, but is displayed because the Web server you connected to has not renewed its SSL certificate. While this does not necessarily mean the site is fraudulent, it does show that the site is less than professional.

CIFS

 CIFS is a standard file system designed for sharing files over the Internet. It is part of the SMB protocol, which allows multiple types of computers to share data and peripherals over a network. CIFS enables users to access files remotely from multiple platforms, including Windows, Mac, Linux, and others.

Client

In the computer world, servers have clients. The "client-server" architecture is common in both local and wide area networks. For example, if an office has a server that stores the company's database on it, the other computers in the office that can access the datbase are "clients" of the server.

On a larger scale, when you access your e-mail from a mail server on the Internet, your computer acts as the client that connects to the mail server. The term "client software" is used to refer to the software that acts as the interface between the client computer and the server. For example, if you use Microsoft Outlook to check your e-mail, Outlook is your "e-mail client software" that allows you to send and receive messages from the server. Isn't exciting how it all works?