-: Layer 6, the presentation layer. 2 2
Now, the presentation layer 3 3
is responsible for formatting your data 4 4
that's going to be exchanged 5 5
and securing the data with proper encryption. 6 6
So, when you think about Layer 6, 7 7
there's a couple of keywords I want you to remember: 8 8
data formatting and encryption. 9 9
Every time we talk about data formatting or encryption, 10 10
I want you to think about Layer 6, 11 11
the presentation layer, inside the OSI model. 12 12
Now, when I talk about data formatting, what is that? 13 13
Well, data is going to be formatted by a computer 14 14
so that it has compatibility between 15 15
different types of devices. 16 16
There are some common ones out there 17 17
that you may or may not have heard of. 18 18
The first one is ASCII, 19 19
which stands for the American Standard 20 20
for Computer Information Interchange. 21 21
Now, ASCII is basically text. 22 22
It's what says that the capital A is represented 23 23
by the number 65. 24 24
In the old days of computers, we had ASCII 25 25
and it was an 8-bit code 26 26
that would tell us exactly what that letter was 27 27
or that symbol, and ASCII characters do that for us. 28 28
For instance, ASCII character 40 29 29
is the @ sign for your email. 30 30
Then, we have things like GIFs 31 31
which are little pictures that dance around and do motion, 32 32
or we have a JPEG file which is used for photographs 33 33
or a PNG which is used for images on the Internet. 34 34
All of these are different types of data formats 35 35
and based on that format, the computer knows 36 36
how to represent it on the screen 37 37
as it passes those files around. 38 38
Because at the end of the day, 39 39
all of these file formats really come down 40 40
to a series of ones and zeros on your computer's hard drive 41 41
or on your network. 42 42
Now, when we talk about ASCII, 43 43
it really is just a text-based language for us to use. 44 44
This is going to ensure that the data is readable 45 45
by the receiving system, 46 46
because now we're all speaking the exact same language. 47 47
Because ASCII isn't the only text-based language out there. 48 48
There's Unicode and a series of other ones. 49 49
But if we all use ASCII, for instance, 50 50
that means we all know 51 51
what the proper data structure is for it 52 52
and the proper formatting. 53 53
This allows us to negotiate data transfer syntax 54 54
for our Layer 7 at the application layer, 55 55
and we're going to talk about that in the next lesson. 56 56
Now, the next piece of this layer, 57 57
or Layer 6, is encryption. 58 58
This is another thing that the presentation layer 59 59
is going to be all about and doing for us. 60 60
Encryption is used to scramble data 61 61
as it goes in transit to keep it secure 62 62
from any prying eyes. 63 63
This is going to provide us with confidentiality 64 64
of our data as it crosses our network and as it's stored. 65 65
Now, some examples of this will be something like TLS 66 66
which stands for Transport Layer Security. 67 67
And that's what's being used right now 68 68
to secure the data between your computer 69 69
and a website like Facebook, or Dion Training, 70 70
or Amazon, or any of the other ones out there. 71 71
If you get that little padlock next to your domain name, 72 72
that means you're using a TLS connection. 73 73
This creates an encrypted tunnel 74 74
so nobody else can see what's inside it 75 75
and that way, they can't see your username, 76 76
your password, and your credit card information 77 77
as you pass it back and forth. 78 78
Now, what are some examples of things at Layer 6? 79 79
Well, things like scripting languages 80 80
are going to be a Layer 6 thing, 81 81
because they're formatting data. 82 82
So, if we're dealing with HTML, or XML, or PHP, or JavaScript, 83 83
all of those tell the text-based ASCII 84 84
how it should display differently on the screen. 85 85
For example, I want to make this line bold 86 86
and make this other one underlined, 87 87
and make this size x font. 88 88
Those type of things can all be controlled 89 89
using a formatting language like HTML 90 90
to take the ASCII code that you typed in 91 91
and translate it into something that looks better 92 92
on the screen. 93 93
We also have things like standard text 94 94
and this would be things like ASCII, or Unicode, or EBCDIC. 95 95
All of these are different ways of displaying text 96 96
from those ones and zeros. 97 97
We also have things like pictures, 98 98
we have GIFs, and JPGs, and TIFs, and SVGs, and PNGs, 99 99
and all of these type of files. 100 100
They're all different ways of representing ones and zeros 101 101
as different graphical formats. 102 102
We also have movie files like MP4s, and MPGs, 103 103
and MOV files, and all of these are going to show up 104 104
as some kind of video for us, 105 105
but they're all made up of these ones and zeros 106 106
in a particular format and that data formatting 107 107
makes it into a movie that you can watch 108 108
just like this video right now. 109 109
So, all of those examples I showed you so far 110 110
are all about presentation, 111 111
presenting text, or images, or photographs, 112 112
or movies in a different way. 113 113
But we also have that example of encryption algorithms. 114 114
Things like TLS and SSL. 115 115
Now, these are taking your ones and zeros 116 116
and presenting them differently, right? 117 117
Because they're scrambling them up 118 118
so nobody else can see them, 119 119
and it secures that data in a jumbled format. 120 120
That's the idea here when you start dealing 121 121
with TLS and SSL. 122 122
So, it is a type of data format, 123 123
but it's not just a clear presentation 124 124
like we had with a movie file, or a graphic file, 125 125
or an audio file, or text. 126 126
Instead, when we start dealing with encryption, 127 127
we're really focused on the security of the data 128 128
by scrambling it up and keeping prying eyes off it.