- [Craig] In this video, we take a look at a range of common protocols you need to know about at GCSE.
(uplifting piano jingle)
So first, let's look at what a protocol actually is.
Let's use this simple analogy.
On the left, we have someone speaking German, and on the right, we have someone speaking English.
These are the only languages these two people know, so when they try to communicate, they're unable to do so.
But what if the person on the left was bilingual?
They can speak German and they can speak English.
They now share a common language, and so the two people can communicate.
This is the principle of a protocol, a set of rules that allow two devices to communicate in some way.
Any computer or device may have many different protocols, with each protocol allowing them to communicate in a different way.
The protocols you need to know about for the exam are listed here.
We're going to go through them briefly now and explain what each one is for.
The first group of protocols we're going to look at are used over the internet.
The first is the transmission control protocol, TCP,
and it provides an error-free way of transmitting data between two routers.
The second is the internet protocol, IP,
and this is responsible for routing packets across a wide area network.
Put them together and you have the TCP-IP protocol stack,
and this is the basic foundation of all communication over the internet.
Now, let's take a look at HTTP and HTTPS.
The hypertext transfer protocol, HTTP,
is a way for a client and server to send and receive requests for and delivery of HTML web pages.
It is a fundamental protocol of the world wide web.
Indeed, when you type in a web address in a web browser and you look at the address at the top,
you will often see HTTP.
You can see this is the protocol being used so that you can receive the web page in your browser.
In a very similar way, there's a protocol called HTTPS,
hypertext transfer protocol secure.
It's effectively the same, except it adds a layer of encryption,
so this tends to be used when a website needs to deal or handle with sensitive information
such as asking for a password to log in or placing an order with credit card information on an online store.
The file transfer protocol is a protocol used for sending files between computers, normally on a wide area network.
It uses a set of common commands, which can be run from the command line for this purpose.
People, however, tend to install FTP clients.
Now, these are simply software applications that sit on top of the actual FTP protocol.
The user interacts with the client program, as shown here, and it generates and sends the appropriate FTP commands.
There are also a whole family of email protocols you need to know about.
The first is the simple mail transfer protocol, SMTP,
and it's used to send an email from a device to an email server.
Now, this doesn't have to be a computer.
You could be on your smartphone, and when you send the email,
the SMTP is the protocol that takes it from your mobile and sends it to the mail server for then sending on to the recipient.
The next is the post office protocol, POP, and it's used by mail clients,
and by that, we mean things like mobiles, laptops, computers and tablets,
and it manages the remote mail box on servers and retrieves email from it.
The important thing to note about POP is it removes the original copy of the email on the server when it's retrieved by the client.
The internet message access protocol, IMAP, is also used by mail clients in a similar way to POP.
However, the importance here is, when the email is retrieved, it leaves the original copy of the email on the server.
So, in this example, I'm out in town and I log on to my mobile phone to check my emails.
Now, I'm assuming I've got a Wi-Fi or a 4G signal, I connect to a remote mail server
and retrieve my latest emails from the mail server using the IMAP protocol.
The original copy of the email, however, remains on the remote mail server.
This means that when I go back into work or I'm home on my laptop,
if I check my email, it's still there.
IMAP prevents different devices from becoming out of sync with each other.
So, here's a brief recap of all the various protocols we've covered and what they do.
(uplifting piano jingle)