What is INTERNET ?
The internet is a vast network of computers, which links many different types of computers all over the world. It is a network of networks, which share a common instrument for identifying computers, and a common set of communication protocols for communication between two computers on the network. It has basically four types of services that are to be provided by the internet to its users which are:
1) Electronic mail - The electronic mail service, it is also known as e-mail allows user to send messages to another internet user in any part of the world in a very short time. The message takes anywhere in just a few seconds to arrive at its destination. It has many similarities with the postal mail services. It facilitates the user to use their email address and has own logical mailbox like each one of us has a mailbox in our house. It also has an alternative to the receivers, either it save or deletes.
Messages in email services can contain not only text documents, but also images, audio and video data. With email services, the Internet has proved to be quick and dynamic communication tool for its users. As compared to paper mail and telephone, email is preferred by many because of its advantages such as under follows:
1. It is more rapidly than paper mail.
2. Unlike telephone, the persons need not be available at the same time.
3. Unlike fax documents, email documents can be stored in a computer, and can be easily edited using editing programs.
2) File Transfer Protocol - The file protocol services, it is also known as FTP allows an internet user to move the file from one computer to another on the internet. A file may contain any type of digital information such as text document, images, artwork, movie, sound, software, etc. Hence, anything that can be stored on a computer can be moved with FTP service. Moving a file from a remote computer to one own computer is known as downloading the file, and moving a file from one’s own computer is known as uploading the file. Its takes place in the following method:
1. A user executes the ftp on his local computer, specifying the address of the remote computer as a parameter.
2. An FTP process running on the user’s computer establishes a link with an FTP process running on the remote computer.
3. The user is the prompted for login name and password to make sure that the user is allowed to access the remote computer.
4. After successful login, the preferred files are downloaded by using get (for downloading) a put (for uploading) commands.
But a user could transfer files from a remote computer, only if he has access rights for the remote computer. With this restriction, it is almost impossible to provide access rights to the vast number of the user of the internet to a computer that contain sharable information. The concept of anonymous FTP site is used to overcome this problem.
The anonymous FTP site is a computer, which allows the user to log in with the username of anonymous and a password that is the user’s email address. The user can than download files from the computers, which have been stored on it for sharing. Such are called publicly reachable sites because they can be accessed by any user on the internet. It is also used for more secure file transfer operations. In such cases, a user needs a valid username and password to access a particular computer.
3) Telnet - The telnet service allows an internet user to log in to another computer somewhere on the internet. That is, a user can execute the telnet command on his local computer to set up a login session on a remote computer. This act is also called “remote login”.
To start a remote login session, the user types the command telnet and the address of the remote computer of the terminal of his local computer. The user than receives the prompt asking to enter a login name i.e. user ID and a password to ensure that the user has the access right for accessing the remote computer. If the user specifies the accurate login name and password, he gets logged in to the remote computer. Once the login session is established with the remote computer, telnet enters the input mode, and anything typed on the terminal of the local computer by the user is sent to the remote computer for processing. It has some common uses such as:
1. Using the computing control of the remote computer. The local computer may be an ordinary personal computer and the remote computer may be powerful super computer.
2. Using software on the remote computer. The software that the user wants to use may not be accessible on the local computer.
3. Accessing remote computer’s database. The information records, such as the public database or library resources may be available on the remote computer.
4. For logging in to one’s own computer from another computer.
4) Usenet News - The Usenet services allow a group of internet users to exchange their views/ideas/information on some common subject, which is of interest to all the members belonging to the group. Several such groups exist on the internet and are called newsgroups.
It is like a notice board, which is accessible to all the members belonging to the group. A member, who wants to exchange his views with another member, sends a specially formatted message, which is processed and interpreted as a notice to be posted on the notice board by the member’s computer, which has an appropriate software running for this purpose. After the processing of the message is over, it can be read or seen from any member’s computer just like a notice posted to the notice board can be read by anyone having access to the notice board.
There are two types of newsgroup. First are moderated group and another one is non moderated group. In moderated newsgroup, only selected people have the right to directly post a message to the virtual notice board, whereas in a non moderated newsgroup, any member can directly post a message to the virtual notice board. In a moderated newsgroup, a message sent by any ordinary member first goes to the computer of one of the selected members having the right to directly post the message to the notice board.
The message is then checked by this member who decides whether the message is appropriate for being posted, and does any editing that might be required to improve the quality of the message. This member than posts the message on the notice board. After this only, the message becomes readable to (can be seen by) other members. The main idea of it is to ensure the quality of the newsgroup.
As no one moderates the quality of the message of a non moderated newsgroup, anyone can post anything. However the member of such newsgroup should be careful in posting a message, because other member may react angrily by sending a flaming message in response to an ill mannered message.
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