A secure location for web hosting servers. Data centers are designed to assure that the servers and the data housed on them are protected from environmental hazards and security breaches.

In general, any outward-bound traffic from a Web site (with the exception of email) is considered to be data transfer. Each time a Web page, image, MIDI file, etc. is loaded, data transfer is generated.

This is any collection of data: part numbers, product codes, customer information, etc. It usually refers to data stored on a computer.

The restoration of a group of compressed files to their original size.

a dedicated line is like a regular telephone line, except that it is only used by one person or business. It is either owned by the user or leased from the phone company.

A dial tone (known in the British Isles as a dialling tone) is a telephony signal used to indicate that the telephone exchange is working and ready to accept a call. The tone stops when the first numeral is dialed, or if there is no response after going off-hook (a timeout), when it is usually followed by a special information tone.

When automated telephone systems were first being deployed, telephone companies noticed that customers were often confused by the apparent lack of response (before this, a telephone operator would answer), and would often assume the phone was not working. To avoid this, exchange systems would play a small buzzing sound into the line instead. Before modern electronic telephone switching systems came into use, dial tones were usually generated by electromechanical means; in the United States, the standard "city" dial tone consisted of a 600 Hz tone amplitude-modulated at 120 Hz. Some dial tones were simply adapted from 60 Hz AC line current.

The modern dial tone varies between countries, being a "buzz" of two interfering tones (350 Hz and 440 Hz, as defined in the Precise Tone Plan) in the NANP (most of North America), and a constant single tone (425 Hz) in most of Europe. Modems, fax machines, and autodialers must be designed to recognise these so-called call-progress tones, as well as comply with differing standards and regulations.

Private or internal PBX or key phone system also have their own dial tone, sometimes the same as the external PSTN one, and sometimes different to remind users to dial a prefix for an outside line.

A "stuttered" dial tone may mean that there is voice mail waiting, or may occur to confirm that a calling feature such as call forwarding has been activated.

Mobile phones do not have dial tones, as the user instead presses "send" to complete the call once the desired phone number is entered.

An experienced guitar player will be able to tune to the dial tone of a phone. The dial tone is a combination of the musical notes 'A' and 'F'.