Understandig the basic concepts of the INTERNET

Copyright Raimondo Ballisti, September 2015
It is my opinion that people can figure out better what is going on when they understand the basic concepts underlying a system like the internet.

Connecting machines together

You can consider the internet as a way to let machines communicate to each others.
Please, note that I am saying "machines communicate" and not users (people). This is the first thing to keep in mind:

internet is a way for MACHINES to communicate to each others.

Machines send information as a series of packets.
Obviously each packet must show the name (address) of the recipient and of the sender.
You can imagine the basic internet service as a conveyor belt as in a sushi bar.
On the conveyor belt you see the packets passing by and you should pick up those which are adressed to you.
This means that everyone can see to whom a paket has been sent and from who. And you can pick up a paket which is not addresses to you, look at its content and then put it back to the conveyor belt!
This shows the problem of keeping information hidden to people who do not need it (and should not see it).
Instead of people around a conveyor belt we have machines listening to the data flow which can be on a wire or by radiowaves or laser beams or whatever the technology will put at our disposition.
The tecnical implementation of the internet data flow is more complex than the idea of the conveyor belt suggests, but the basic concept remains the same:
 <=========== carrier of data ============== data flow ==========> (conveyor belt)
      |              |              |             |            |
      |              |              |             |            |
   machine       machine         machine       machine      machine
You immediately see the necessity to hide sensitive information from access by unauthorized machines (persons).
One first step is to encrypt the data which are inside the pakets.
This till leave the sender and the recipient visible, but hides the content of the paket, which is usually the most important thing to do.
Modern browser succed today in doing this and you can check that your data are encrypted by looking at the address of the connecting site: instead of "http" you will see "https".
Please note the extra "s " after "http". This means that the data are encrypted.

Please note that in the above I spoke of "browser". This do not apply to others utilities as for instance to mailtools.

Utilities (programmes) which use the internet connection

We have to add another step to our understanding of how the whole thing around internet works.
I wrote above that the internet is a method for machines to communicate to each others.
It is only "inside" the machine that some programmes allow users (also persons) to take advantage of this machine's communication in order to communicate and exchange information.
One of those programmes is called "browser", of which many kind exists (Internet Explorer, Firefox, Safari, Google Chrome, etc).
If you need to send or receive sensitive data, as for instance the password to your bank account, you need to make sure that this important information is encripted. As I wrote above, https must be active. You cannot activate it by yourself: the utility that you are using (for instance a bank account connection) must put it to your disposition. NEVER send a password if the data are not encripted: it is a risk.

Another popular programme is the mailtoool, of which a huge number exists (Outlook, Thunderbird, Google Mail, Mail of the Mac, etc).
Mailtools do not have this "https" possibility, but they can encrypt mails in different ways, that I cannot describe here because it is matter for a special chapter.
Here a simple sketch of the distinction between "user", "programme", "machine", "internet"
                               user (may be you)
      This is your machine      |
      |                         |                             |
      |            ----------------------------               |
      |            |         two of the       |               |
      |         browser      most used    mailtool            |
      |            |         programme        |               |
      |            |                          |               |
      |            ----------------------------               |
      |                         |                             |
      |                   ethernet unit                       |
      |                         |                             | 
     <<<<<<<<<<<<<<<<<<< connection to the internet >>>>>>>>>>>>>>>
I have introduced here a new word: "ethernet unit".
This is to emphasis the hardware part of the whole picture.
What I have been describing above was a concept, i.e. the underlying concept which end up in that thing called internet.
But the tecnical implementation is a bit more complex than that, and the concept of "ethernet" is one of the basic "cornerstone of the building".

The implementation of the INTERNET concept

Every machine (it could be a Personal Computer or just a gadget in your car) get from the factory an unique "ethernet number" also called ethernet address or MAC Address, see
Wikipedia: MAC address .
Often those numbers are given in a format as in this example:
It is important to keep in mind the difference between the "ethernet address" which is the deepest hardware "name" for your machine and the internet address which looks like as in this example:
IP address:
(IP means INTERNET PROTOCOL which in short is a rule to be followed, a kind of agreement between all users).
The convey belt of which I spoke at the very beginning of this chapter cannot work for the whole planet. So a way as been found to reduce the number of machine using the same "convey belt" in creating a kind of tree which end up in branches on which only fewer "leaves", i.e. our machines, are connected.
This magic as been realised using the "internet address" which is assigned to a machine before the first connection in a local network, and is depending of the network in which you are connecting your machine.
See also: Wikipedia: Internet Address
That means that your Portable Computer will work with differents internet addresses depending on your location. But the hardware address, the "ethernet number" mentionned before, this must be the same.