Every computer on earth is unique in its own right. I mean unique, not
in terms of its brand or operating system. Certainly, this is not what
sets your machine apart from others.
By machine, this refers to anything with a processing unit, be it a
mobile phone or a desktop computer. All these devices can be
classified as computing machines.
Now, this uniqueness is what defines a machine's identity in the same
way your identity is defined by not only your name, but even more
important by your personality.
This has the advantage of identifying one machine from the other in a
If you want to communicate with someone, they have to know your
personal details. These could be
- Your name
Either in full or nickname. Anything that sets you
apart from whoever are around you.
I think this one is the most important thing of all:
It could be a traditional physical address;
a postal office address;
Or your electronic address such as your email, Twitter ID or
- Your phone number
It could be a fixed or mobile phone.
But why bother about this concept of addressing?
Because that is exactly what is behind computers: every computer has
its own address to which other machines address their messages.
Let us put it this way: the idea of machines communicating is modelled
along the same lines as human communication. In particular, transport.
A port is a point of departure and arrival. From this outlook, it
means computers use ports to send and receive messages.
Even within a computer itself: the way it transports information from
one component to the other, for instance a keyboard to the processor, is
made possible because of these ports.
However, we are simply interested in how two different machines find
each other on the network: this is made possible by the controlling
hub or server. This server registers all machine IDs.
For the sake of this discussion, this is a mail server. However, it
reflects any other communication that takes place through other
Your machine has dedicated ports to receive and send messages. These
are in brief,
|25||Outgoing Unencrypted for POP|
|110||Incoming Unencryptted for POP|
|995||Incoming (secure) for POP|
|993||Incoming (secure) for IMAP|
|465||Secure outgoing for IMAP|
From the above table, you will notice that we have ports for incoming
and outgoing messages, for either PO or IMAP. Below we will get into
that in detail.
For the meantime, let's talk about how our email addresses are formed.