Part 1 - Application of Internet

Application of Internet

World Wide Web (WWW)

The World Wide Web (WWW) is combination of all resources and users on the Internet that are using the Hypertext Transfer Protocol (HTTP).

A broader definition comes from the World Wide Web Consortium (W3C):

"The World Wide Web is the universe of network-accessible information, an embodiment of human knowledge."

The Web, as it's commonly known, is often confused with the internet. Although the two are intricately connected, they are different things. The internet is, as its name implies, a network -- a vast, global network that incorporates a multitude of lesser networks. As such, the internet consists of supporting infrastructure and other technologies. In contrast, the Web is a communications model that, through HTTP, enables the exchange of information over the internet.

Tim Berners-Lee is the inventor of the Web and the director of the W3C, the organization that oversees its development. Berners-Lee developed hypertext, the method of instant cross-referencing that supports communications on the Web, making it easy to link content on one web page to content located elsewhere. The introduction of hypertext revolutionized the way people used the internet.

In 1989, Berners-Lee began work on the first World Wide Web server at CERN. He called the server "httpd” and dubbed the first client "WWW.” Originally, WWW was just a WYSIWYG hypertext browser/editor that ran in the NeXTStep environment. 

The World Wide Web has been widely available since 1991.

Search Engine

A web search engine is a software system that is designed to search for information on the World Wide Web. The search results are generally presented in a line of results often referred to as search engine results pages (SERPs). The information may be a mix of web pages, images, and other types of files. Some search engines also mine data available in databases or open directories. Unlike web directories, which are maintained only by human editors, search engines also maintain real-time information by running an algorithm on a web crawler.

On the Internet, a search engine is a coordinated set of programs that includes:

• A spider (also called a "crawler" or a "bot") that goes to every page or representative pages on every Web site that wants to be searchable and reads it, using hypertext links on each page to discover and read a site's other pages
• A program that creates a huge index (sometimes called a "catalog") from the pages that have been read
• A program that receives your search request, compares it to the entries in the index, and returns results to you

An alternative to using a search engine is to explore a structured directory of topics. Yahoo, which also lets you use its search engine, is the most widely-used directory on the Web. A number of Web portal sites offer both the search engine and directory approaches to finding information.

Different Search Engine Approaches

• Major search engines such as Google, Yahoo (which uses Google), AltaVista, and Lycos index the content of a large portion of the Web and provide results that can run for pages - and consequently overwhelm the user.
• Specialized content search engines are selective about what part of the Web is crawled and indexed. For example, TechTarget sites for products such as the AS/400 (http://www.search400.com) and CRM applications (http://www.searchCRM.com) selectively index only the best sites about these products and provide a shorter but more focused list of results.
• Ask Jeeves (http://www.ask.com) provides a general search of the Web but allows you to enter a search request in natural language, such as "What's the weather in Seattle today?"
• Special tools and some major Web sites such as Yahoo let you use a number of search engines at the same time and compile results for you in a single list.
• Individual Web sites, especially larger corporate sites, may use a search engine to index and retrieve the content of just their own site. Some of the major search engine companies license or sell their search engines for use on individual sites.

Google is the world's most popular search engine, with a marketshare of 80.52 percent as of March, 2017.

The world's most popular search engines (with >1% market share) are:

Search engine	Market share in March 2017
Google	80.52%
Bing	6.92%
Baidu	5.94%
Yahoo!	5.35%

East Asia and Russia

In some East Asian countries and Russia, Google is not the most popular search engine.

In Russia, Yandex commands a marketshare of 61.9 percent, compared to Google's 28.3 percent. In China, Baidu is the most popular search engine. South Korea's homegrown search portal, Naver, is used for 70 percent of online searches in the country. Yahoo! Japan and Yahoo! Taiwan are the most popular avenues for internet search in Japan and Taiwan, respectively.

Remote Login

Remote access may refer to:

• Connection to a data-processing system from a remote location, for example, through a Remote Access Service or virtual private network
• Remote desktop software, software allowing applications to run remotely on a server while displaying graphical output locally
• Terminal emulation - when used to interface with a remote system. May use standard tools like:
• telnet - software used to interact over a network with a computer system
• ssh - secure shell: often used with remote applications
• Activation of features of a business telephone system from outside the business's premises
• RemoteAccess, a DOS-based bulletin-board system
• Remote Database Access, a protocol standard for database access

Rlogin (remote login) is a UNIX command that allows an authorized user to login to other UNIX machines (hosts) on a network and to interact as if the user were physically at the host computer.

Telnet

Telnet is a protocol used on the Internet or local area networks to provide a bidirectional interactive text-oriented communication facility using a virtual terminal connection. User data is interspersed in-band with Telnet control information in an 8-bit byte oriented data connection over the Transmission Control Protocol (TCP).

Telnet was developed in 1969 beginning with RFC 15, extended in RFC 854, and standardized as Internet Engineering Task Force (IETF) Internet Standard STD 8, one of the first Internet standards. The name stands for "teletype network".

Telnet (short for TErminal NETwork) is a network protocol used to provide a command line interface for communicating with a device.

Telnet is used most often for remote management but also sometimes for the initial setup for some devices, especially network hardware like switches, access points, etc.

Managing files on a website is also something Telnet is sometimes used for.

Telnet is sometimes written in uppercase as TELNET and may also be misspelled as Telenet.

How Does Telnet Work?

Telnet used to be used mainly on a terminal, or a "dumb" computer. These computers require only a keyboard because everything on the screen is displayed as text. There is no graphical user interface like you see with modern computers and operating systems.

The terminal provides a way to remotely log on to another device, just as if you were sitting in front of it and using it like any other computer. This method of communication is of course done via Telnet.

Nowadays, Telnet can be used from a virtual terminal, or a terminal emulator, which is essentially a modern computer that communicates with the same Telnet protocol.

One example of this is the Telnet command, available from within the Command Prompt in Windows. The telnet command, unsurprisingly, is a command that uses the Telnet protocol to communicate with a remote device or system.

Telnet commands can also be executed on other operating systems like Linux, Mac, and Unix, much in the same was as you would in Windows.

Telnet is not the same thing as other TCP/IP protocols like HTTP, which just let you transfer files to and from a server. Instead, the Telnet protocol has you log on to a server as if you were an actual user, granting you direct control and all the same rights to files and applications as the user that you're logged in as.

FTP

The File Transfer Protocol (FTP) is a standard network protocol used for the transfer of computer files between a client and server on a computer network.

FTP is built on a client-server model architecture and uses separate control and data connections between the client and the server. FTP users may authenticate themselves with a clear-text sign-in protocol, normally in the form of a username and password, but can connect anonymously if the server is configured to allow it. For secure transmission that protects the username and password, and encrypts the content, FTP is often secured with SSL/TLS (FTPS). SSH File Transfer Protocol (SFTP) is sometimes also used instead; it is technologically different.

The first FTP client applications were command-line programs developed before operating systems had graphical user interfaces, and are still shipped with most Windows, Unix, and Linux operating systems. Many FTP clients and automation utilities have since been developed for desktops, servers, mobile devices, and hardware, and FTP has been incorporated into productivity applications, such as web page editors.

File Transfer Protocol (FTP) is the commonly used protocol for exchanging files over the Internet. FTP uses the Internet's TCP/IP protocols to enable data transfer. FTP uses a client-server architecture, often secured with SSL/TLS. FTP promotes sharing of files via remote computers with reliable and efficient data transfer.

How FTP Works

FTP works in the same way as HTTP for transferring Web pages from a server to a user's browser and SMTP for transferring electronic mail across the Internet in that, like these technologies.

FTP uses a client-server architecture. Users provide authentication using a sign-in protocol, usually a username and password, however some FTP servers may be configured to accept anonymous FTP logins where you don't need to identify yourself before accessing files. Most often, FTP is secured with SSL/TLS.

FTP is most commonly used to download a file from a server using the Internet or to upload a file to a server (e.g., uploading a web page file to a Web server).

Electronic Mail (Email)

Electronic mail, or email, is a method of exchanging digital messages between people using digital devices such as computers, mobile phones and other electronics. Email first entered substantial use in the 1960s and by the mid-1970s had taken the form now recognized as email. Email operates across computer networks, which today is primarily the Internet. Some early email systems required the author and the recipient to both be online at the same time, in common with instant messaging. Today's email systems are based on a store-and-forward model. Email servers accept, forward, deliver, and store messages. Neither the users nor their computers are required to be online simultaneously; they need to connect only briefly, typically to a mail server or a webmail interface, for as long as it takes to send or receive messages.

Originally an ASCII text-only communications medium, Internet email was extended by Multipurpose Internet Mail Extensions (MIME) to carry text in other character sets and multimedia content attachments. International email, with internationalized email addresses using UTF-8, has been standardized, but as of 2017 it has not been widely adopted.

The history of modern Internet email services reaches back to the early ARPANET, with standards for encoding email messages published as early as 1973 (RFC 561). An email message sent in the early 1970s looks very similar to a basic email sent today. Email had an important role in creating the Internet, and the conversion from ARPANET to the Internet in the early 1980s produced the core of the current services.

Types

Web-based email

Many email providers have a web-based email client (e.g. AOL Mail, Gmail, Outlook.com, Hotmail and Yahoo! Mail). This allows users to log into the email account by using any compatible web browser to send and receive their email. Mail is typically not downloaded to the client, so can't be read without a current Internet connection.

POP3 email services

The Post Office Protocol 3 (POP3) is a mail access protocol used by a client application to read messages from the mail server. Received messages are often deleted from the server. POP supports simple download-and-delete requirements for access to remote mailboxes (termed maildrop in the POP RFC's).

IMAP email servers

The Internet Message Access Protocol (IMAP) provides features to manage a mailbox from multiple devices. Small portable devices like smartphones are increasingly used to check email while travelling, and to make brief replies, larger devices with better keyboard access being used to reply at greater length. IMAP shows the headers of messages, the sender and the subject and the device needs to request to download specific messages. Usually mail is left in folders in the mail server.

MAPI email servers

Messaging Application Programming Interface (MAPI) is used by Microsoft Outlook to communicate to Microsoft Exchange Server - and to a range of other email server products such as Axigen Mail Server, Kerio Connect, Scalix, Zimbra, HP OpenMail, IBM Lotus Notes, Zarafa, and Bynari where vendors have added MAPI support to allow their products to be accessed directly via Outlook.