BT glossary - S

This glossary is here to help you understand some of the acronyms you may encounter in this site. Select a letter below that your word begins with.

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Abbreviation Term Definition



Secure Internet Protocol

A secure form of the Internet protocol, which uses public key encryption techniques to provide integrity, confidentiality and authentication of IP data packets.



Secure Sockets Layer

A protocol designed by Netscape Communications to enable encrypted, authenticated communications across the internet. SSL used mostly (but not exclusively) in communications between web browsers and web servers. URL's that begin with https indicate that an SSL connection will be used. SSL provides three important things; privacy, authentication, and message integrity. In an SSL Connection each side of the connection must have a security certificate, which each side's software sends to the other. Each side then encrypts what it sends using information from both its own and the other side's certificate, ensuring that only the intended recipient can de-crypt it, and that the other side can be sure the data came from the place the it claims to have come from, and that the message has not been tampered with.


Security certificate

A chunk of information (often stored as a text file) that is used by the SSL protocol to establish a secure connection. Security certificates contain information about who it belongs to, who it was issued by, a unique serial number or other unique identification, valid dates, and an encrypted fingerprint that can be used to verify the contents of the certificate. In order for an SSL connection to be created both sides must have a security certificate.



Service Level Agreement

Defines how a service should perform and the sanctions if it fails to perform.


Service provider

DSL broadband services are usually bought through a service provider, eg, BT



Using a high speed broadband connection, it's easy to share large data files - your music, photos and videos - with others around the world.



Software that is freely distributed on the basis that if you find it useful, you should pay the author.



Short Messages Service

Used to convey text messages between digital mobile phones.



Simple Mail Transfer Protocol

The standard protocol for transferring electronic mail from one computer to another through the Internet.



Simple Network Management Protocol

A set of standards for communication with devices connected to a TCP/IP network. Examples of these devices include routers, hubs, and switches. A device is said to be SNMP compatible if it can be monitored and /or controlled using SNMP messages. SNMP messages are known as PDU's - Protocol Data Units. Devices that are SNMP compatible contain SNMP agent software to receive, send, and act upon SNMP messages. Software for managing devices via SNMP are available for every kind of commonly used computer and are often bundled along with the device they are designed to manage. Some SNMP software is designed to handle a wide variety of devices.



Small Office Home Office

An industry segment including sole traders, home workers and others.



Small to Medium-sized Enterprise



Smart card

A tamper-resistant hardware device the size of a credit card, that can be used for the storage of secure information such as personal information, electronic cash and private encryption keys. More advanced cards can also be used to carry out tasks such as encryption and decryption, so that the private key is never revealed to even the owner of the card.



A smiling face on its side i.e. :-) used to inject a bit of humour or expression in electronic mail messages. A smiley is an emoticon (q.v.)



The computer programs that make the hardware work and provide the tools and facilities you want to use.



The maximum amount of information you can receive over your line at one time, measured in Kilo (thousands) or Mega (millions) bits (binary digits) per second. Speed and 'bandwidth' are different ways of describing broadband capacity.



Pretending to be someone or something else.


Spread spectrum

A digital radio transmission technique in which the signal is 'chirped' against a much faster code sequence so that it spreads out to occupy the whole of the radio frequency spectrum available to it. A large number of spread spectrum transmissions can occupy the same frequencies together with narrow band signals from other sources (including 'interferers') without mutual interference.



Spyware is software that covertly gathers user information through the user's internet connection without his or her knowledge, usually for advertising purposes. Spyware applications are typically bundled as a hidden component of free or to share software programs that can be downloaded from the internet; however, it should be noted that the majority of shareware and freeware applications do not come with spyware. Once installed, the spyware monitors user activity on the internet and transmits that information in the background to someone else. Spyware can also gather information about e-mail addresses and even passwords and credit card numbers.



Standard and Generalised Markup Language

A document formatting language, allowing meaning and formatting to be associated with text. The parent language for HTML and XML.



A broadcast flow of continuous broadband information such as a sports event or a live concert broadcast.



A customer of a telephone company or administration.



Subscriber Trunk Dialling

This term is used when customers dial their own long-distance calls.



The name for the UK academic virtual private network based on SMDS.



Making your way around the worldwide web from site to site.



An alternative word for exchange



Switched Multimegabit Data Service

This is the WAN equivalent of LAN, SMDS is the ATM connectionless service.



Switched Virtual Circuit

A switched virtual circuit is established as needed, as opposed to a pvc Permanent Virtual Circuit which has to be pre-established. see Virtual Circuit.



Synchronous Data Link Control

This is the dominant IBM layer two protocol used in first-age (mainframe - terminal) networks.



Synchronous Digital Hierarchy

A technique for assembling and transmitting component digital signals, for example for individual phone calls, into a single high bit rate digital data stream.