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 Internet - Web browsers, W.W.W. , Email, Search    Engines, Meta and Entity Search Engines           

  Internet                                                                                                

 • Internet full from International Network. 

 • Internet is a network of computer, which links many different types of computer all over the world. 

 • VINT CURF is known as father of computer. 

 • Internet is a network that connects computers all over the world through  the internet, people can shaw information and  communication from anywhere with an  internet connection. 

 • The data move around the internet is controlled by protocols. 

 • It uses TCP/IP protocol (Transmission Control Protocal / Internet Protocol) in which a file is broken into small a parts called as PACKETS by file servecs. 

 • In 1969 university of California at las Angeles and university of UTAM begining of ARPANET. 

 • ARPANET full form Advanced Research Projects Agency Network. 

 • It was the world's first operational switching network. 

 • The goal of this project is to connect computers at different universities and us defence. 

 • Inmid 80 another federal agency. 

 • NSF (National Science Foundation) started  a new high capacity network called NSF net which  was move capable than ARPANETA. 

 • Drowback - The only drawback of NSF net was that it allowed only the academic research an its network and not any kind of private business on it. 

 • IPS reffers to the company that provides internet connections to the uses. 

 • Some POP was ISP are Airtel, Vodafone etc. 

 • First ISP in India was launched by VSNL (Videsh Sanchar Nigam limited). 

 • First ISP in the world was Telnet which was introduced in 1974. 

   Internet protocols                                                                               

 • TCP (Transmission Contral Protocal) 

 TCP is a connection oriented protocol and offers end to end packet delivery. It acts as back bone for connection. It exhibits the following key features: Transmission Control Protocol (TCP) corresponds to the Transport Layer of OSI Model. TCP offers connection oriented end to end Packet delivery. TCP ensures reliability by sequencing bytes with a forwarding acknowledgement number that indicates to the destination the next byte the source expect to receive. 

 IP (Internet Protocol) 

 Internet protocol is connectionless and unreliable protocol. It ensures on guarantee  of successfully transmission of data. In order to make it reliable, it must be paired with reliable protocol such as TCP at the transport layer. 

 UDP (User Datagram Protocol) 

 Like IP, UDP is connectionless and unreliable  protocol. It doesn't require making a connection  with the host to exchange  data. Since UDP is unreliable protocol, there is no mechanism for ensuring that data sent its received. 

 TFTP (Trivial File Transfer Protocol) 

 Trivial File Transfer Protocol is also used to transfer the files but it transfers the files without authentication. Unlike FTP, TFTP does not separate control and data information. Since there is no authentication exists, TFTP lacks in security features therefore it is not recommended to use TFTP. 

 Telnet 

 Telnet is a protocol used to log in to remote computer on the internet. There are a number of telnet clients having user friendly user interface. The following  diagram shows a person is logged into computer A, and from there, he remote logged into computer B.  

HTTP (Hyper Text Transfer Protocol)  

HTTP is a communication protocal. It defines mechanism for communication between browser and the web server. It its also called request and response protocol because the communication between  browser and server takes place in request and response pairs. HTTP is used to access the data w.w.w.

 HTTP are the combination of FTP and SMTP (Simple Mail Transfer Protocol). HTTP massages are delivaed immediately. HTTP uses the services of TCP on well known port no 80 . 

 HTTPS - Hyper Text Transfer Protocal Security. 

 Web Browsers                                                                                       

• Web browsers is a software application. 

 • It is used to locate, retrieve and also display content on the world wide web (W.W.W.) 

 • Web browsers are basically used to explore the internet. 

 • More than one web browser can be installed on a single computer.  

  Types of web browsers                               

 i. Text Web Browsers 

 A web browser that displays only text based information is known as text web browsers. Example LYNX which provides access to the internet in text mode only. 

 ii. Graphical Web Browsers 

 • A web browser that supports both text and graphic information is known as graphical web browser. 

 • Major graphical web browsers are internet explore, firefox, chrome, safari, opera mini, opera. 

 • The first graphical web browser was NCSA. (National Centre for Supercomputers Application).

  Popular Graphical Web Browsers    

 1. NETSCAPE 

 • Netscape was introduced on 4 April 1994. 

 • Netscape browser was once dominant but lost to internet explorer and other competitors in the SD called first  browser was. 

 • Market shaw fallen from more than 90% in the mid 1990 to less than 1% in 2006. 

 2. INTERNET EXPLORER 

 • It is a product of Microsoft. 

 • This was introduced in 1995 along with windows 95 launch and it has passed netscape popularity in 1998. 

 • It was once the most widely used web browser attaining a peak of about 95% usage shace by 2003. 

 • Usage shace declined with the launch of fire Fox (2004) and chrome (2008). 

 3. Mozilla Fire Fox 

 It was published in 2004 and grown to be the second most popular web browser. 

 4. Google Chrome 

 This web browser was developed by google in 2008. 

 5. Safari 

 This web browsers was developed by Apple Incorporation in 2003. 

 6. EDGE 

 Microsoft weared in edge web browser in 2015 as part of windows 10. 

    WWW (World Wide Web) 1989                                                         

The internet is often confused with the world wide web. The misperception is that these teo terms are synonymous. The internet is the collection of the many different systems and protocols. 

 The world wide web developed in 1989 in Tim Berners lee is actually one of these different protocol. As the name implies, it allows resources of be linked with great ease in an almost seamless fashion. The would wide web contains a vast collection of linked multimedia pages that is even changing. However, there are several basic components  of the web that allow users to communicate  with each other. Below you will f ind selected components and their descriptions. 

 One reason was that commercial companies and the general public were allowed to connect to the internet. Another reason was that www and mosaic were invented and the use of the internet became much friendier. 

   E-mail (Electronic-mail)                                                                   

 An e-mail server organizes its information in units called mail messages. Messages are stored in mail boxes. When mail messages are transferred between e-mail servers, a protocol called SMTP, Simple Mail Transfer Protocol, is used. When you retrieve messages from the e-mail  server to your computer a protocol called POP3 (Post Office Protocol) version 3 is used. 

 Email Structure 

 From - Won E-mail ID 

 To - Send E-mail ID 

CC - (Carbon Copy)  

BCC (Bline Carbon Copy) 

 Subject -  Compose email - Type your email. 

 • Short for electronic mail, e-mail or email is information stored on a computer that is exchanged between two users over telecommunications. More plainly, email is a message that may contain text, files, images or other attachments sent through a network to a specified individual or group of individuals. 

 • The first e-mail was send by Roy Tomlinson in 1971 

 CC - A cc, short for "Carbon Copy" is a copy of an email message sent to a  recipient whose email address appears  in the message's CC header field. 

 Email Address : An email address is a name for an electronic postbox that can receive (and send) email messages on a network (such as the internet or a local network not connected to the wider internet.) 

 Email Body : An email body is the main part of an email message that contains the message's text, images and other data (such as attached files)

Email Client : An email client is a program (on a computer or mobile device, for example) used to read and send electronic memages. 

 SMTP (Simple Mail Transfer Protocol) SMTP, short for Simple Mail Transfer. Protocol, is the protocol used for email on the internet. It defines a message format and a procedure to route messages through the internet from source to destination via email servers. 

 IMAP (Internet Messaging Access Protocol) IMAP shopt for Internet Messaging Accesse Protocol, is an internet standard that describes a protocol for retrieving mail from an email (IMAP) server. IMAP allows email programs to access not only new messages but also folders on the server. Actions are synchronized between multiple email programs connected through IMAP. 

 Mail to - Mailto is an HTML tag that allows visitors to a site to click on a link that creates a new message in their default email program. It is possible to set not only a default email recipient but also default subject and message body content. 

 Phishing - Phishing is a fraudulent practice in which private data is captured on websites or through an email designed to look like a trusted third party. Typically, phishing (from "Password  f ishing") scams involve an email alerting the user to a problem with their bank or another account. 

POP (Post Office Protocol) - POP is an internet standard that defines an email server and a way to retrieve  mail from it. In contrast to IMAP, POP only lets the email client download recent messages, to be managed in the program and on the device. 

 Spam - Spam is unsolicited email. Not all unsolicited  email is spam, however. Most spam is sent in bulk  to a large number of email addresses and advertises some product or - considerably less often - political viewpoint. 

 Spammer - 1 A spammer is a person on entity (such as a company) that sends spam emails. 

 To : The To. line of an email contains its primary recipient or recipients. All recipients in the To: line is visible to all other recipients, possibly by default. 

 Unicode : Unicode is a way to represent characters  and symbols on computers and devices  with support for most of the world's writing systems (including African, Arabic, Asian and western). 

 Subject : The subject of an email message should ba a short summary of its contents. Email programs usually display it in a mailbox display together with the sender. 

 Threadjacking : Threadjacking (also thereadwhacking) is to steer off the original topic in an email thread, especially on a mailing list. Threadjacking can also apply to other conversations on the internet, of course, say on message boards, blogs or social networking sites. Whether the threadjacker changes the subject line to reflect the change in subject or retains the original email subject to take over a thread can be regarded as threadjacking in either case.

Worm : A worm is a program or script that replicates itself and moves through a network, typically traveling by sending new copies of itself via email. Many worms have no negative effect except  resource consumption, but some will perform malicious actions. 

 Search Engines                                                                                    

 Search Engine refers to a huga database of internet resources such as web pages, newsgroups, programs, images etc. It helps to locate information on world wide web. User can search for any information by passing query in form of keywords or phrase. It them searches for relevant information in its database and return to the user. 

 Search Engine are complex computer software programmes designed to search an information on the world wide web and provide users the best results in fastest possible way. google, yahoo, bing are most used search engines. 

 Search Engine Components             

 Generally there are three basic components of a search engine as listed below :  

i. web crawler : It is also known as spider or bots. It is a software component that traverses the web to gather information. 

 ii. Index / Database : All the information on the web is stored in database. It consists of huge web resources. 

 iii. Search Interface or results : This component is an interface between user and the database. It helps the user to search through the database. 

   Search Engine Working        

 Web crawler, database and the search interface  are the major component of a search engine that actually makes search engine  to work. Search engines make use of Boolean expression AND, OR, NOT to restrict and widen the results of a search. Following are the steps that are performed by the search engine :  

i. The search engine looks for the keyword in the index for predefined database instead of going directly to the web to search for the keyword. 

 ii. It then uses software to search for the information in the database. This software component is known as web crawler. 

 iii. Once web crawler finds the pages, the search engine then shows the relevant web pages as a result. These retrieved web pages generally include title of pages, size of text portion, first several sentences etc. 

 Examples. — Google, Bing - 2009, Ask - 1996,  Alta Vista - 1995, AOL. Search, Lycos, Alexa.

   Different types of Search Engines          

1. Semantic search/Major Search Engines 

 • DuckDuckGo 

 • KNGINE 

 2. Meta Search Engines  

• Poly Meta 

 • Ixquick 

 3. Advance Search Engines 

 • Mamma  

4. People Search Engines 

 • Spokeo 

• Peek you 

 5. Industry / organization search

 • Linkedln 

 • Glassdoor 

 6. Collective Media Search Engines 

 • Social mention 

 • Social Searcher 

 7. Knowledge Base Search Engines 

 • Health Mash 

 Meta and Entity Search Engines                                                        

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