WEB SEARCH ENGINE

A Web search engine is a search engine designed to search for information on the World Wide Web. Information may consist of web pages, images, information and other types of files. Some search engines also mine data available in newsbooks, databases, or open directories. Unlike Web directories, which are maintained by human editors, search engines operate algorithmically or are a mixture of algorithmic and human input.How Web search engines work


Web search engines work by storing information about many web pages, which they retrieve from the WWW itself. These pages are retrieved by a Web crawler (sometimes also known as a spider) — an automated Web browser which follows every link it sees. Exclusions can be made by the use of robots.txt. The contents of each page are then analyzed to determine how it should be indexed (for example, words are extracted from the titles, headings, or special fields called meta tags). Data about web pages are stored in an index database for use in later queries. Some search engines, such as Google, store all or part of the source page (referred to as a cache) as well as information about the web pages, whereas others, such as AltaVista, store every word of every page they find. This cached page always holds the actual search text since it is the one that was actually indexed, so it can be very useful when the content of the current page has been updated and the search terms are no longer in it. This problem might be considered to be a mild form of linkrot, and Google's handling of it increases usability by satisfying user expectations that the search terms will be on the returned webpage. This satisfies the principle of least astonishment since the user normally expects the search terms to be on the returned pages. Increased search relevance makes these cached pages very useful, even beyond the fact that they may contain data that may no longer be available elsewhere.

When a user enters a query into a search engine (typically by using key words), the engine examines its index and provides a listing of best-matching web pages according to its criteria, usually with a short summary containing the document's title and sometimes parts of the text. Most search engines support the use of the boolean operators AND, OR and NOT to further specify the search query. Some search engines provide an advanced feature called proximity search which allows users to define the distance between keywords.

The usefulness of a search engine depends on the relevance of the result set it gives back. While there may be millions of webpages that include a particular word or phrase, some pages may be more relevant, popular, or authoritative than others. Most search engines employ methods to rank the results to provide the "best" results first. How a search engine decides which pages are the best matches, and what order the results should be shown in, varies widely from one engine to another. The methods also change over time as Internet usage changes and new techniques evolve.

Most Web search engines are commercial ventures supported by advertising revenue and, as a result, some employ the practice of allowing advertisers to pay money to have their listings ranked higher in search results. Those search engines which do not accept money for their search engine results make money by running search related ads alongside the regular search engine results. The search engines make money every time someone clicks on one of these ads.

Revenue in the web search portals industry is projected to grow in 2008 by 13.4 percent, with broadband connections expected to rise by 15.1 percent. Between 2008 and 2012, industry revenue is projected to rise by 56 percent as Internet penetration still has some way to go to reach full saturation in American households. Furthermore, broadband services are projected to account for an ever increasing share of domestic Internet users, rising to 118.7 million by 2012, with an increasing share accounted for by fiber-optic and high speed cable lines

WEB PRESS

Offset printing


Offset printing is a commonly used printing technique where the inked image is transferred (or "offset") from a plate to a rubber blanket, then to the printing surface. When used in combination with the lithographic process, which is based on the repulsion of oil and water, the offset technique employs a flat (planographic) image carrier on which the image to be printed obtains ink from ink rollers, while the non-printing area attracts a water-based film (called "fountain solution"), keeping the non-printing areas ink-free.

Ira Washington Rubel invented the first offset printing press in 1903.[1]


Offset printing advantages

Advantages of offset printing compared to other printing methods include:

* Consistent high image quality. Offset printing produces sharp and clean images and type more easily than letterpress printing because the rubber blanket conforms to the texture of the printing surface.
* Quick and easy production of printing plates.
* Longer printing plate life than on direct litho presses because there is no direct contact between the plate and the printing surface. Properly developed plates running in conjunction with optimized inks and fountain solution may exceed run lengths of a million impressions.
* The more you print, the less you pay per page, because most of the price goes into the preparation undergone before the first sheet of paper is printing and ready for distribution. Any additional paper print will only cost the client paper price (and ink), which is very minimal.
Offset printing disadvantages

Disadvantages of offset printing compared to other printing methods include:

* Slightly inferior image quality compared to rotogravure or photogravure printing.
* Propensity for anodized aluminum printing plates to become sensitive (due to chemical oxidation) and print in non-image/background areas when developed plates are not cared for properly.

Photo offset


The most common kind of offset printing is derived from the photo offset process, which involves using light-sensitive chemicals and photographic techniques to transfer images and type from original materials to printing plates.

In current use, original materials may be an actual photographic print and typeset text. However, it is more common — with the prevalence of computers and digital images — that the source material exists only as data in a digital publishing system.

Offset litho printing on to a web (reel) of paper is commonly used for printing of newspapers and magazines for high speed production.

WEB DECORATIONS

Web decorations, sometimes termed stabilimenta (the plural of stabilimentum), are conspicuous silk structures included in their webs by some species of orb-web spider.
Content.
Origin

It is likely that the use of stabilimenta evolved independently at least nine different times. Araneus and Gasteracantha make silk stabilimenta, while Cyclosa and the closely related Allocyclosa bifurca make silk, detritus, and egg sac stabilimenta. All those evolved independently from those of Argiope, although some decorations of A. bifurca closely resemble the ones from Argiope.

Form

Although web decorations are common in a number of spider species in the families Araneidae, Tetragnathidae and Uloboridae, they are probably best known from spiders of the genus Argiope that includes a number of species known as the St. Andrew's Cross spider, so named for its habit of resting in its web with its legs outstretched in the shape of an X, the traditional shape of the cross of St. Andrew. However, spiders in this genus also construct web decorations as a vertical line and juveniles commonly construct disc-shaped decorations[2]. Other spiders also construct round structures covering the entire hub of the web.
Function

There is much controversy surrounding the function of these structures, and it is likely that different species use it for different purposes. Some people believe that they provide protection to the spider by either camouflaging it or making it appear larger. Another theory is that they make the spider visible and therefore animals such as birds are less likely to damage the spider’s web[3]. Originally the decorations were thought to stabilize the web (hence the term stabilimentum), but this is dismissed nowadays. One more recent theory is that web decorations attract prey by reflecting ultraviolet light[4]. Light in the ultraviolet part of the spectrum is known to be attractive to many species of insects[4]. Many other theories have also been proposed such as thermoregulation , stress, regulation of excess silk, or simple esthetics.

One theory has been put forward that the purpose of the stabilimentum is to attract the male of the species to the web when the female is ready to reproduce. A limited study[5] carried out in the Calahonda area of Spain in the summer of 1992 showed that there was a positive correlation between the presence of a male in the webs of Argiope lobata and the presence of a stabilimentum.

While many Ulcerous species construct stabilization, Uloborus gibbosus does not; it usually rests at an edge of its orb and drops to the ground if disturbed. This is thought to support the web camouflage hypothesis. The strongly UV-reflecting stabilimentum of the uloborid Octonoba sybotides was found to be attractive to Dorsophila flies[1]

Materials

While the most conspicuous and well-studied decorations are constructed entirely of silk (for example in Cyclosa), some spiders combine silk with other items such as egg sacs and debris. It seems likely that these decorations camouflage the spider, thus providing protection against predators[6]. However, one interesting case occurs in some species of the golden orb spiders in the genus Nephila. These spiders commonly attach lines of uneaten prey items to their webs. Recent studies have shown that these items help the spider to attract more prey[7].

WEB PAGE RANKING

page rank

Mathematical Page Ranks (out of 100) for a simple network (Page Ranks reported by Google are rescaled logarithmically). Page C has a higher Page Rank than Page E, even though it has fewer links to it: the link it has is much higher valued. A web surfer who chooses a random link on every page (but with 15% likelihood jumps to a random page on the whole web) is going to be on Page E for 8.1% of the time. (The 15% likelihood of jumping to an arbitrary page corresponds to a damping factor of 85%.) Without damping, all web surfers would eventually end up on Pages A, B, or C, and all other pages would have Page Rank zero. Page A is assumed to link to all pages in the web, because it has no outgoing links.
Mathematical Page Ranks (out of 100) for a simple network (Page Ranks reported by Google are rescaled logarithmically). Page C has a higher Page Rank than Page E, even though it has fewer links to it: the link it has is much higher valued. A web surfer who chooses a random link on every page (but with 15% likelihood jumps to a random page on the whole web) is going to be on Page E for 8.1% of the time. (The 15% likelihood of jumping to an arbitrary page corresponds to a damping factor of 85%.) Without damping, all web surfers would eventually end up on Pages A, B, or C, and all other pages would have Page Rank zero. Page A is assumed to link to all pages in the web, because it has no outgoing links.

Page Rank is a link analysis algorithm that assigns a numerical weighting to each element of a hyper linked set of documents, such as the World Wide Web, with the purpose of "measuring" its relative importance within the set. The algorithm may be applied to any collection of entities with reciprocal quotations and references. The numerical weight that it assigns to any given element E is also called the Page Rank of E and denoted by PR(E).

The name Page Rank is a trademark of Google. The Page Rank process has been patented (U.S. Patent 6,285,999 ). The patent is assigned to Stanford University and not to Google. Google has exclusive license rights on the patent from Stanford University. The university received 1.8M shares in exchange for the patent. The shares were sold in 2005 for $336M

WEB PORTAL

A web portal is a site that provides a single function via a web page or site. Web portals often function as a point of access to information on the World Wide Web. Portals present information from diverse sources in a unified way. Apart from the search engine standard, web portals offer other services such as e-mail, news, stock prices, infotainment, and other features. Portals provide a way for enterprises to provide a consistent look and feel with access control and procedures for multiple applications, which otherwise would have been different entities altogether. An example of a web portal is Yahoo!.

History

In the late 1990s the web portal was a hot commodity. After the proliferation of web browsers in the mid-1990s many companies tried to build or acquire a portal, to have a piece of the Internet market. The web portal gained special attention because it was, for many users, the starting point of their web browser. Netscape became a part of America Online, the Walt Disney Company launched Go.com, and Excite and @Home became a part of AT&T during the late 1990s. Lycos was said to be a good target for other media companies such as CBS.

Many of the portals started initially as either web directories (notably Yahoo!) or search engines (Excite, Lycos, AltaVista, infoseek, Hotbot were among the earliest). Expanding services was a strategy to secure the user-base and lengthen the time a user stayed on the portal. Services which require user registration such as free email, customization features, and chatrooms were considered to enhance repeat use of the portal. Game, chat, email, news, and other services also tend to make users stay longer, thereby increasing the advertising revenue.

The portal craze, with "old media" companies racing to outbid each other for Internet properties, died down with the dot-com flameout in 2000 and 2001. Disney pulled the plug on Go.com, Excite went bankrupt and its remains were sold to iWon.com. Some notable portal sites ― Yahoo!, for instance ― remain successful to this day. The portal craze serves as a cautionary tale to modern dot-com businesses about the risks of rushing into a market crowded with highly-capitalized but largely undifferentiated me-too companies.