Internet 
Introduction
The services provided over these infrastructures are, and will be even more so in the future, fundamentally interactive multimedia services that require a wide variety of technologies to be able to attend to the whole process necessary to carry them out properly.
The so-called information highways are the set of physical media and the information that travels through them to enable all types of communications. The physical media that will support the information highways are the national information infrastructures that are linked together to form a network of networks or global infrastructure.
our definition of the term "Internet". "Internet" refers to the global information system that:
(1) is logically linked by a globally unique address space based on the Internet Protocol (IP) or its subsequent extensions/continuations.
(2) is capable of supporting communications using the Transmission Control Protocol/Internet Protocol (TCP/IP) suite or its subsequent extensions/continuations, and/or other IP-compatible protocols.
(3) And provides, uses, or makes available, either publicly or privately, high-level services provided by the communications and related infrastructure.
4.1. Basic Services
are classified as
Communication Services
Electronic mail, E-mail
Stakeholders, News
It is probably the most widespread service on the Internet. There is always a simple and cheap way to communicate by e-mail. This service allows the exchange of electronic messages with any user of the Internet (and other networks). There are multimedia extensions (MIME) that allow you to send any type of information associated with a message: data, text, sound, images, etc.
This service can be used to create discussion platforms on a variety of topics, since it allows questions to be sent out into the world to be answered by someone, giving rise to virtual round tables.
The service operates on a client-server model. Numerous programs exist for a user to act as a client, and to establish news sessions for both multi-user computers and personal computers.
The most common operations are:
- Subscribe to the desired interest group(s).
- Select a group for consultation.
- Browse the headlines of the group's articles.
- Read, save or print selected articles.
- Send a reply or a new message to the group.
- Reply privately by e-mail to the author of a new article.
Virtual terminal, Telnet
Allows the client station to become a user terminal of the target machine, to use its utilities or access its data. Its use is usually restricted for security reasons.
¿What happens in the telnet client?
- A TCP/IP connection to the server is established.
- Accepts data from the local terminal (keyboard).
- Converts the local data to a standard format.
- Sends it over the network to the server.
- Accepts data from the server in a standard format.
File transfer, FTP
FTP applications offer a file transfer service, allowing the transfer of information (anything that can be stored in a file) between two computers.
Search Mechanisms
Archie
Archie is one of the oldest search services that allows you to locate a program or document on the Internet, files, especially in "anonymous" FTP servers, returning information about where it is located, generating a database, so that it can be accessed later.
Geographical distribution
- archie.rutgers.edu: NE USA
- archie.sura.net: SE USA
- archie.unl.edu: W USA
- archie.mcgill.ca: Canada
- archie.au: Australia
- archie.switch.ch: Europe
- archie.doc.ic.ac.uk: Europe
- archie.rediris.es: Europe
Gopher
This service is oriented to take a look at the resources available, rather than to search for something specific. It was developed at the University of Minnesota, and allows you to search for resources using menus and browsing inside computers, going through their directories, as if you were a gopher.
How Gopher works:
The user contacts his local server.
The local server sends the menu.
The corresponding menu item is selected.
The server informs about the type of selection:
- Path to a file and host for FTP.
- Host and login for Telnet.
- Directory server.
- Other submenu
The user saves his current state to return to it if needed.
Gopher accesses the selected resource.
Subsequently it is possible to return to the previous state. if it was saved. In many cases states can be stored stably.
4.2. Internet architecture
On the Internet there are machines dedicated to specific and therefore specialized tasks.
The backbone, in practice is formed by a set of high-speed lines that initially crossed the United States from coast to coast, and later extended to cover the rest of the world, especially the western world, and to which all Internet gateways are connected.
The gateways, using their own protocol (within TCP-IP) are in charge of routing data packets. To do this, the memories of these machines store information related to the sub-networks that hang from all the other Internet gateways and, of course, from their own.
Servers. These are the machines on which the applications of the different services that can be used on the Internet reside. For example: World Wide Web servers, e-mail servers, chat servers.
DNS (domain name servers): Their function is to relate IP addresses to domain names.
End users: By connecting to their servers, which are the Internet access providers, they form a local network.
Client: These are the programs that reside on the end users' computers, and which, connected to the corresponding server, allow them to use the services that exist on the network.
4.3. Electronic mail
Electronic mail (or e-mail) was designed so that two people could exchange letters using the regular postal service.
The first regular mail software allowed only this basic function: a person on a computer typed a message that was sent, via the Net, to another person using another computer, but from here on a new form of communication was opened up that combined the speed of the telephone with the permanence of postal mail.
Today's e-mail systems support more complete services that allow more complex actions such as:
Send the same message to many people.
Include text, voice, video or graphics.
Connect with a user outside the Internet.
Send messages automatically, from a computer, etc.
E-mail messages, like old documents, have a formal structure. They begin with a header that specifies:
- the sender (from:),
- the addressee (to: or for:),
- the day and time it was sent (date:),
- and what it is about (topic: or subject:),
When a user sends a message, the software that handles the message contacts the receiver's computer, using the e-mail address, and transfers a copy of the message (using the standard protocol that controls file transfer on the Internet, TCP), which is stored in the receiver's mailbox, and the receiver is notified at the same time. To ensure the quality of the transmission, the sending computer keeps a complete copy of the message during the transfer.
4.4. Electronic Commerce
E-commerce is a means of enabling and supporting such changes on a global scale. It enables companies to be more efficient and more flexible in their internal operations, to work more closely with their suppliers and to better respond to their customers' needs and expectations. It enables them to select the best suppliers, regardless of their geographic location, and to sell in a global marketplace.
depending on the agents involved, can be subdivided into four different categories:
company-company
company-consumer
company-administration
consumer-administration
E-commerce offers a variety of opportunities for suppliers and multiple benefits for customers/consumers:
Opportunities for suppliers:
global presence
increased competitiveness
mass customization & customization
shorter delivery chains non-existent
substantial cost reduction
new business opportunities.
Customer benefits
/ global choice
/ quality of service
/ customized products & services
quick response to needs / quick response to needs
/ substantial price reduction
/ new products & services.
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