T&C - Abbreviation for Terms and Conditions.

T1 - Network transmission line capable of transferring data at 1.544 Mbps.

T3 - Network transmission line capable of transferring data at 44.746 Mbps.

Taxonomy - A set of agreed-upon principles according to which information can more logically be stored in an information retrieval system. The term is used in science to describe the classification of natural elements.

TB - Terabyte 1,000,000,000,000 Bytes = 1 Million Megabytes

Technorati - An Internet search engine that specifically indexes Weblogs and attempts to provide more up-to-the-minute results the traditional search engines.

TEP - Abbreviation for Trusted Email Provider

Term Vectors - In the classic vector-space retrieval model, documents and queries are converted to term vectors to allow documents to be matched to queries and ranked based on the number of times the search terms occur in each document.

Termination Page - The termination pages can be accessed via links from the core but do not link back into the core.

Text Ad - An advertisement using text-based hyperlinks.

Text Link - A plain text link that does not use images. Text links are usually blue and underlined. Text links are what "spiders" or "robots" use to go from one web page to another.

Text Link Ads - These are ads that are completely text based. They normally consist of a title, description and an URL. Many search engines and directories use text link ads. They are also popular to drive customers to your site as well as add important links to your site that will improve your page rank.

Text Link Exchange - The network where participating web sites display text ads in exchange for credits that are converted into ads to be displayed on other sites.

TF - Abbreviation for Term Frequency. A measure of how often a term is found in a collection of documents. TF is combined with inverse document frequency (IDF) as a means of determining which documents are most relevant to a query. TF is sometimes also used to measure how often a word appears in a specific document.

TH - Abbreviation for Transmission Control Protocol

TH - Language Code for Thai

THB - Currency Code for Thailand Baht

THE - Trusted Hosting Environment

The Deep Web - The content in databases that rarely shows up in Web searches. It is estimated that there are 500 billion Web pages that could potentially be hidden.

The Description Tag - The Meta tag content that is visible on the SERP with engines that support this tag. Description Tag should not exceed 170 characters including spaces.

The Human Involved - A process obtaining directories listings is far different than with obtaining listings in spider-built search indexes or paid search-advertising engines.

The Keywords Tag - See Keyword Tag

The Search Engine Results Page - The first page user see after entered query into the search box. The page lists results of the search query, sorted in terms of relevancy. (see also: SERP)

The Title Tag - The Meta Tag containing data that appears as a title of web page. Also its create the short line of text appear on search engine’s result page. Title Tag should not exceed 50 characters including spaces.

Theme - The website's main topic. Also could refer to design layout.

Theme Engine - A type of search engine that attempts to automatically classify sites based on the keywords they contain.

Thesaurus - A list of synonyms a search engine can use to find matches for particular words if the words themselves not appear in documents.

Thin Affiliates - Doorways that send visitors to affiliate programs, earning a commission for doing so, while providing little or no value-added content or service to the user.

Threadwatch - A marketing and technology forum aiming for "less noise and more signal".

Throwaway Domain - A domain where the name itself has little value to the owner. Throwaway domains are typically used to experiment with. It's common among search engine spammers to register throwaway domains to experiment with things like cloaking. Unethical SEO providers sometimes use throwaway domains to build link popularity to a client's site. This can backfire though as search engines are continually finding better ways to combat Spam.

Tier 2 Search Engines - Smaller Search Engines

TIF - Abbreviation for Tagged Image File Format also file extension: filename.tif

TIFF - Abbreviation for Tagged Image File Format filename.tiff

Title - See The Title Tag

Title Tag - See The Title Tag

TLD - Abbreviation for Top Level Domain. Most commonly thought of as a ".com", also includes ".org" and ".edu"

TM - Abbreviation for Trademark (T)

TOM - Abbreviation for Tactical Online Marketing The process of informing the customer of your services from various sources.

Toolbar - With reference to search engines, toolbars are browser add-ons provided by the search engines. These toolbars often include a search box, shortcuts to the different sections of the search engine, additional page information etc.

Top 10 - The top ten search engine results for a particular search term.

Top Level Page - The root default page usually index.html, index.htm, default.asp etc. Often search engines request to submit only your top-level page, then they spider will find the rest of website pages from there.

TOS - Abbreviation for Terms Of Service, usually could be found in a contract, also known as the contracts "deliverables".

Trackback - The method used to notify another blog that you wrote in your blog about them

Tracking URL - Usually used in PPC campaigns, it is a URL that has special code added to it so that results can be monitored.

Traffic - The term is used to describe activity on a web site - be it hits, page views or unique visitors. Also refers to the number of visitors, hits, accesses etc. over a given period.

Traffic Death Redesign - This sudden and dramatic loss of traffic occurs when a web site is re-designed and the page names all change. The result is that aside from the main URL, none of the old pages exist anymore, and anyone clicking on a search engine listing gets a 404, or "page not found" error unless other measures are taken.

Transactional Query - A query where the user expects to conduct a transaction.

T-Rex - The name of the Lycos spider.

Trick Banner - A banner ad that attempts to trick people into clicking, often by imitating an operating system message.

Trulia - A vertical search engine for real estate.

Trusted Feed - A form of paid inclusion which uses bulk a XML feed to directly send website content to search engines for indexing. The feed can be optimized so that your website can take advantage better rankings and therefore more traffic.

Trusted Feed - see XML feed

TrustRank - A method of using a combination of limited human site review in conjunction with a search engines algorithm.

TTFB - Abbreviation for Time To First Byte

Turbo10 - A Meta search engine that is searches both the surface-web normal documents and the invisible web or, as they call it, the DeepNet the documents that is not indexed by normal search engines. www.turbo10.com

TWD - Currency Code for Taiwan New Dollars

Two Tier Affiliate Program - An affiliate program structure whereby affiliates earn commissions on their conversions as well as conversions of webmasters they refer to the program.

TXT - Abbreviation for Text File also file extension: filename.txt

Typeless Search Engine - A search engine that perform searches via voice recognition, clicks of a mouse or any means other than typing a keyword.

Typosquatting - Relies on typographical errors by users to serve up websites that look like well-known websites to launch viruses and Trojans to unsuspecting users.