1 00:00:00,780 --> 00:00:03,600 Layer Six, The Presentation Layer. 2 00:00:03,600 --> 00:00:05,100 Now the presentation layer 3 00:00:05,100 --> 00:00:07,260 is responsible for formatting your data 4 00:00:07,260 --> 00:00:08,520 that's going to be exchanged 5 00:00:08,520 --> 00:00:11,490 and securing the data with proper encryption. 6 00:00:11,490 --> 00:00:13,470 So when you think about layer six, 7 00:00:13,470 --> 00:00:15,540 there's a couple of keywords I want you to remember. 8 00:00:15,540 --> 00:00:18,060 Data formatting and encryption. 9 00:00:18,060 --> 00:00:21,000 Every time we talk about data formatting or encryption, 10 00:00:21,000 --> 00:00:22,980 I want you to think about layer six, 11 00:00:22,980 --> 00:00:26,100 the presentation layer inside the OSI model. 12 00:00:26,100 --> 00:00:29,100 Now when I talk about data formatting, what is that? 13 00:00:29,100 --> 00:00:31,560 Well, data is going to be formatted by a computer 14 00:00:31,560 --> 00:00:33,000 so that it has compatibility 15 00:00:33,000 --> 00:00:34,950 between different types of devices. 16 00:00:34,950 --> 00:00:36,330 There are some common ones out there 17 00:00:36,330 --> 00:00:38,280 that you may or may not have heard of. 18 00:00:38,280 --> 00:00:40,620 The first one is ASCII, which stands for 19 00:00:40,620 --> 00:00:43,890 the American Standard Code for Information Interchange. 20 00:00:43,890 --> 00:00:46,440 Now, ASCII is basically text. 21 00:00:46,440 --> 00:00:48,240 It's what says that the capital A 22 00:00:48,240 --> 00:00:50,790 is represented by the number 65. 23 00:00:50,790 --> 00:00:53,370 In the old days of computers, we had ASCII, 24 00:00:53,370 --> 00:00:54,780 and it was an eight bit code 25 00:00:54,780 --> 00:00:56,940 that would tell us exactly what that letter was 26 00:00:56,940 --> 00:00:58,020 or that symbol, 27 00:00:58,020 --> 00:00:59,970 and ASCII characters do that for us. 28 00:00:59,970 --> 00:01:02,130 For instance, ASCII character 40 29 00:01:02,130 --> 00:01:04,200 is the @ sign for your email. 30 00:01:04,200 --> 00:01:06,720 Then we have things like gifs, which are little pictures 31 00:01:06,720 --> 00:01:08,400 that dance around and do motion, 32 00:01:08,400 --> 00:01:11,310 or we have a JPEG file, which is used for photographs 33 00:01:11,310 --> 00:01:14,280 or a PNG, which is used for images on the internet. 34 00:01:14,280 --> 00:01:16,980 All of these are different types of data formats, 35 00:01:16,980 --> 00:01:19,140 and based on that format, the computer knows 36 00:01:19,140 --> 00:01:20,940 how to represent it on the screen 37 00:01:20,940 --> 00:01:22,860 as it passes those files around. 38 00:01:22,860 --> 00:01:24,300 Because at the end of the day, 39 00:01:24,300 --> 00:01:26,700 all of these file formats really come down 40 00:01:26,700 --> 00:01:29,790 to a series of ones and zeros on your computer's hard drive 41 00:01:29,790 --> 00:01:31,200 or on your network. 42 00:01:31,200 --> 00:01:32,490 Now when we talk about ASCII, 43 00:01:32,490 --> 00:01:35,520 it really is just a text-based language for us to use. 44 00:01:35,520 --> 00:01:37,560 This is going to ensure that the data is readable 45 00:01:37,560 --> 00:01:38,850 by the receiving system 46 00:01:38,850 --> 00:01:42,090 because now we're all speaking the exact same language 47 00:01:42,090 --> 00:01:45,000 because ASCII isn't the only text-based language out there. 48 00:01:45,000 --> 00:01:47,670 There's Unicode and a series of other ones. 49 00:01:47,670 --> 00:01:50,940 But if we all use ASCII for instance, that means we all know 50 00:01:50,940 --> 00:01:52,740 what the proper data structure is for it 51 00:01:52,740 --> 00:01:54,270 and the proper formatting. 52 00:01:54,270 --> 00:01:56,694 This allows us to negotiate data transfer syntax 53 00:01:56,694 --> 00:01:59,610 for our layer seven at the application layer, 54 00:01:59,610 --> 00:02:01,950 and we're going to talk about that in the next lesson. 55 00:02:01,950 --> 00:02:03,690 Now the next piece of this layer, 56 00:02:03,690 --> 00:02:05,760 of layer six is encryption. 57 00:02:05,760 --> 00:02:07,800 This is another thing that the presentation layer 58 00:02:07,800 --> 00:02:10,199 is going to be all about in doing for us. 59 00:02:10,199 --> 00:02:13,380 Encryption is used to scramble data as it goes in transit 60 00:02:13,380 --> 00:02:15,810 to keep it secure from any prying eyes. 61 00:02:15,810 --> 00:02:18,630 This is going to provide us with confidentiality of our data 62 00:02:18,630 --> 00:02:21,660 as it crosses our network and as it's stored. 63 00:02:21,660 --> 00:02:24,438 Now some examples of this will be something like TLS, 64 00:02:24,438 --> 00:02:27,270 which stands for Transport Layer Security, 65 00:02:27,270 --> 00:02:28,920 and that's what's being used right now 66 00:02:28,920 --> 00:02:30,960 to secure the data between your computer 67 00:02:30,960 --> 00:02:34,860 and a website like Facebook or Dion Training or Amazon 68 00:02:34,860 --> 00:02:36,510 or any of the other ones out there. 69 00:02:36,510 --> 00:02:39,390 If you get that little padlock next to your domain name, 70 00:02:39,390 --> 00:02:42,120 that means you're using a TLS connection. 71 00:02:42,120 --> 00:02:43,680 This creates an encrypted tunnel 72 00:02:43,680 --> 00:02:46,080 so nobody else can see what's inside it, 73 00:02:46,080 --> 00:02:48,780 and that way they can't see your username, your password, 74 00:02:48,780 --> 00:02:50,160 and your credit card information 75 00:02:50,160 --> 00:02:52,260 as you pass it back and forth. 76 00:02:52,260 --> 00:02:55,320 Now what are some examples of things at layer six? 77 00:02:55,320 --> 00:02:57,300 Well, things like scripting languages 78 00:02:57,300 --> 00:02:58,890 are going to be a layer six thing 79 00:02:58,890 --> 00:03:00,450 because they're formatting data. 80 00:03:00,450 --> 00:03:03,500 So if we're dealing with HTML or XML or PHP 81 00:03:03,500 --> 00:03:07,620 or JavaScript, all of those tell the text-based ASCII 82 00:03:07,620 --> 00:03:10,410 how it should display differently on the screen. 83 00:03:10,410 --> 00:03:12,660 For example, I want to make this line bold 84 00:03:12,660 --> 00:03:14,400 and make this other one underlined 85 00:03:14,400 --> 00:03:16,500 and make this size X font. 86 00:03:16,500 --> 00:03:18,570 Those type of things can all be controlled 87 00:03:18,570 --> 00:03:21,270 using a formatting language like HTML 88 00:03:21,270 --> 00:03:23,610 to take the ASCII code that you typed in 89 00:03:23,610 --> 00:03:25,010 and translate into something 90 00:03:25,949 --> 00:03:26,782 that looks better on the screen. 91 00:03:26,782 --> 00:03:28,890 We also have things like standard text, 92 00:03:28,890 --> 00:03:33,480 and this would be things like ASCII or Unicode or EBCDIC. 93 00:03:33,480 --> 00:03:35,910 All of these are different ways of displaying text 94 00:03:35,910 --> 00:03:37,890 from those ones and zeros. 95 00:03:37,890 --> 00:03:39,480 We also have things like pictures. 96 00:03:39,480 --> 00:03:44,100 We have GIFs and JPEGs and TIFs and SVGs and PNGs, 97 00:03:44,100 --> 00:03:45,780 and all of these type of files. 98 00:03:45,780 --> 00:03:48,150 They're all different ways of representing ones and zeros 99 00:03:48,150 --> 00:03:50,070 as different graphical formats. 100 00:03:50,070 --> 00:03:54,990 We also have movie files like MP4s and MPEGs and MOV files, 101 00:03:54,990 --> 00:03:56,730 and all of these are going to show up 102 00:03:56,730 --> 00:03:58,380 as some kind of video for us, 103 00:03:58,380 --> 00:04:00,630 but they're all made up of these ones and zeros 104 00:04:00,630 --> 00:04:02,280 in a particular format, 105 00:04:02,280 --> 00:04:04,710 and that data formatting makes it into a movie 106 00:04:04,710 --> 00:04:07,800 that you can watch just like this video right now. 107 00:04:07,800 --> 00:04:09,990 So all of those examples I showed you so far 108 00:04:09,990 --> 00:04:11,490 are all about presentation, 109 00:04:11,490 --> 00:04:14,790 presenting text or images or photographs or movies 110 00:04:14,790 --> 00:04:15,840 in a different way. 111 00:04:15,840 --> 00:04:18,750 But we also have that example of encryption algorithms, 112 00:04:18,750 --> 00:04:21,390 things like TLS and SSL. 113 00:04:21,390 --> 00:04:23,460 Now these are taking your ones and zeros 114 00:04:23,460 --> 00:04:25,624 and presenting them differently, right? 115 00:04:25,624 --> 00:04:26,490 Because they're scrambling them up 116 00:04:26,490 --> 00:04:27,780 so nobody else can see them, 117 00:04:27,780 --> 00:04:30,810 and it secures that data in a jumbled format. 118 00:04:30,810 --> 00:04:31,740 That's the idea here. 119 00:04:31,740 --> 00:04:33,870 When you start dealing with TLS and SSL. 120 00:04:33,870 --> 00:04:35,580 So it is a type of data format, 121 00:04:35,580 --> 00:04:37,560 but it's not just a clear presentation 122 00:04:37,560 --> 00:04:39,990 like we had with a movie file or a graphic file 123 00:04:39,990 --> 00:04:41,940 or an audio file or text. 124 00:04:41,940 --> 00:04:43,920 Instead, when we start dealing with encryption, 125 00:04:43,920 --> 00:04:46,200 we're really focused on the security of the data 126 00:04:46,200 --> 00:04:48,783 by scrambling it up and keeping prying eyes off it.