1 00:00:00,750 --> 00:00:02,678 So let's start this course 2 00:00:02,678 --> 00:00:05,269 with the most important question first, 3 00:00:05,269 --> 00:00:10,269 what exactly is web development and connected to that, 4 00:00:10,530 --> 00:00:12,870 what does this mean for us web developers? 5 00:00:12,870 --> 00:00:15,470 What exactly do web developers do, 6 00:00:15,470 --> 00:00:17,420 and what happens when we, 7 00:00:17,420 --> 00:00:21,450 as a regular user enter an address like amazon.com 8 00:00:21,450 --> 00:00:24,580 in the browser and the Amazon website loads up. 9 00:00:24,580 --> 00:00:26,830 What's happening behind the scenes? 10 00:00:26,830 --> 00:00:29,960 As a web developer or as an aspiring web developer 11 00:00:29,960 --> 00:00:32,830 especially, you must be able to understand this 12 00:00:32,830 --> 00:00:35,570 because this will help you understand which kind of code 13 00:00:35,570 --> 00:00:39,200 you will have to write and how the "thing", the internet, 14 00:00:39,200 --> 00:00:42,210 you're working with actually works. 15 00:00:42,210 --> 00:00:44,900 Now to come back to the first two questions, 16 00:00:44,900 --> 00:00:48,640 what is web development and what do web developers do? 17 00:00:48,640 --> 00:00:52,600 Well there, the answer is indeed pretty straightforward. 18 00:00:52,600 --> 00:00:56,240 Web developers generally build websites. 19 00:00:56,240 --> 00:00:57,800 I'm saying generally, 20 00:00:57,800 --> 00:01:00,410 because as you will learn throughout this course, 21 00:01:00,410 --> 00:01:03,200 there are other kinds of things 22 00:01:03,200 --> 00:01:05,370 web developers can build as well. 23 00:01:05,370 --> 00:01:09,070 And even websites are made up of multiple pieces. 24 00:01:09,070 --> 00:01:10,990 And it's depends on the website 25 00:01:10,990 --> 00:01:14,940 and the complexity of a website, which pieces are involved. 26 00:01:14,940 --> 00:01:17,030 That being said in this course, 27 00:01:17,030 --> 00:01:18,610 you're going to learn all of that. 28 00:01:18,610 --> 00:01:20,420 You're going to learn how to build simple 29 00:01:20,420 --> 00:01:23,610 and more complex websites, how to write code 30 00:01:23,610 --> 00:01:26,330 that's invisible to most users, 31 00:01:26,330 --> 00:01:30,730 as well as how to write code that affects what users see, 32 00:01:30,730 --> 00:01:34,890 and you will learn how to build so-called web services. 33 00:01:34,890 --> 00:01:38,720 And what that is as well, but we'll dive into that later. 34 00:01:38,720 --> 00:01:40,150 So it's all in this course, 35 00:01:40,150 --> 00:01:42,281 but generally as a web developer, 36 00:01:42,281 --> 00:01:46,710 you build websites and therefore this actually leads 37 00:01:46,710 --> 00:01:48,890 to another important question. 38 00:01:48,890 --> 00:01:50,504 What's happening behind the scenes 39 00:01:50,504 --> 00:01:55,504 when a visitor, like you, enters an address like amazon.com 40 00:01:56,200 --> 00:01:59,630 in the browser, how does the web actually work? 41 00:01:59,630 --> 00:02:01,620 What's happening there? 42 00:02:01,620 --> 00:02:03,010 And to understand this, 43 00:02:03,010 --> 00:02:07,010 I want to take a step back and look at a real world analogy 44 00:02:07,010 --> 00:02:10,680 because browsing the web and the visiting a website 45 00:02:10,680 --> 00:02:13,670 is actually like calling a friend you could say, 46 00:02:13,670 --> 00:02:16,180 or sending a text message to a friend. 47 00:02:16,180 --> 00:02:18,840 This is an analogy we can make. 48 00:02:18,840 --> 00:02:20,900 In the effort to understand this, 49 00:02:20,900 --> 00:02:24,900 let's actually take a closer look at this analogy. 50 00:02:24,900 --> 00:02:29,150 When you call a friend, you in the end, pick up the phone, 51 00:02:29,150 --> 00:02:32,880 you dial their number or you send a text message to them. 52 00:02:32,880 --> 00:02:35,130 And once the connection was established, 53 00:02:35,130 --> 00:02:39,030 once they pick up the call, you tell them something, 54 00:02:39,030 --> 00:02:42,420 or you ask something, you greet them, whatever. 55 00:02:42,420 --> 00:02:45,730 You start a conversation with your friend. 56 00:02:45,730 --> 00:02:49,710 And after you greet them and maybe told them something, 57 00:02:49,710 --> 00:02:52,810 or you asked something at some point, 58 00:02:52,810 --> 00:02:56,440 your friend will probably reply to you. 59 00:02:56,440 --> 00:02:59,460 He, or she will say something to you 60 00:02:59,460 --> 00:03:02,900 or send back a another text message. 61 00:03:02,900 --> 00:03:05,370 So that's how we have a conversation on the phone. 62 00:03:05,370 --> 00:03:09,200 We say something, they say something. And so on. 63 00:03:09,200 --> 00:03:12,500 Now, visiting a website is pretty much the same. 64 00:03:12,500 --> 00:03:16,340 There you are sitting on your computer or laptop 65 00:03:16,340 --> 00:03:20,370 using your browser because that's the key entry tool 66 00:03:20,370 --> 00:03:23,550 that we need to visit a website. We need a browser for this, 67 00:03:23,550 --> 00:03:26,170 as you probably know, because you're using it every day. 68 00:03:26,170 --> 00:03:30,905 And in that browser, you enter an address like amazon.com 69 00:03:30,905 --> 00:03:33,270 or maybe you searched for Amazon 70 00:03:33,270 --> 00:03:35,400 and you clicked a search result link, 71 00:03:35,400 --> 00:03:38,483 but either way you end up with an address like this 72 00:03:38,483 --> 00:03:41,510 in the browser address bar. 73 00:03:41,510 --> 00:03:45,000 Now this address thing has actually an official name. 74 00:03:45,000 --> 00:03:45,833 It's called URL, 75 00:03:46,740 --> 00:03:49,620 which stands for a uniform resource locator. 76 00:03:49,620 --> 00:03:51,150 But I'll come back to this later, 77 00:03:51,150 --> 00:03:52,710 you enter an address like this. 78 00:03:52,710 --> 00:03:56,250 And then what happens next is that your browser sends 79 00:03:56,250 --> 00:03:59,495 a so-called request to some remote computer 80 00:03:59,495 --> 00:04:02,455 out there in the internet, out there in the world, 81 00:04:02,455 --> 00:04:07,420 a computer operated by the company that owns the website, 82 00:04:07,420 --> 00:04:09,190 which you're trying to visit. 83 00:04:09,190 --> 00:04:12,290 So in this case, some computer operated by Amazon. 84 00:04:12,290 --> 00:04:14,720 Your browser sends a request to it. 85 00:04:14,720 --> 00:04:18,769 And this process is standardized because in web development, 86 00:04:18,769 --> 00:04:21,283 many things are standardized to ensure 87 00:04:21,283 --> 00:04:23,920 that the different parties that are involved 88 00:04:23,920 --> 00:04:27,120 like the browser and this remote computer do speak 89 00:04:27,120 --> 00:04:29,360 the same kind of language. 90 00:04:29,360 --> 00:04:31,460 The standard thats involved here 91 00:04:31,460 --> 00:04:34,820 for controlling that such a request is sent. 92 00:04:34,820 --> 00:04:38,524 And that this request is structured in a standardized way 93 00:04:38,524 --> 00:04:40,520 is called HTTP, 94 00:04:40,520 --> 00:04:43,665 which stands for hypertext transfer protocol, 95 00:04:43,665 --> 00:04:48,665 or often you'll see HTTPS where the S stands for secure, 96 00:04:48,980 --> 00:04:51,500 which means that the communication is encrypted 97 00:04:51,500 --> 00:04:54,970 between browser and this remote computer. 98 00:04:54,970 --> 00:04:57,030 Now, you don't need to worry too much about this 99 00:04:57,030 --> 00:04:59,700 because that's the standard the browser will use 100 00:04:59,700 --> 00:05:02,257 by default but that's the explanation 101 00:05:02,257 --> 00:05:06,588 why sometimes in some URLs you see something like 102 00:05:06,588 --> 00:05:11,588 HTTP://, or HTTPS:// in front of the address. 103 00:05:14,340 --> 00:05:17,310 It's typically added automatically by the browser, 104 00:05:17,310 --> 00:05:19,450 because that is the default protocol 105 00:05:19,450 --> 00:05:23,153 that is being used for talking to this remote computer. 106 00:05:24,010 --> 00:05:26,000 Now on this remote machine, 107 00:05:26,000 --> 00:05:29,560 we then in the end have the website code that's required 108 00:05:29,560 --> 00:05:31,360 for showing something on the screen. 109 00:05:31,360 --> 00:05:34,700 And this code of course, is written by web developers. 110 00:05:34,700 --> 00:05:38,860 In this example, here, web developers working for Amazon. 111 00:05:38,860 --> 00:05:42,240 Now this website code can be of different complexity, 112 00:05:42,240 --> 00:05:45,646 and there can be more complex steps involved 113 00:05:45,646 --> 00:05:47,820 for producing this code. 114 00:05:47,820 --> 00:05:49,080 But we're going to learn that 115 00:05:49,080 --> 00:05:50,879 throughout the course step-by-step. 116 00:05:50,879 --> 00:05:51,712 In the end, 117 00:05:51,712 --> 00:05:55,191 this code holds a bunch of browser instructions though 118 00:05:55,191 --> 00:05:58,960 that tell the browser what it should display on the screen. 119 00:05:58,960 --> 00:06:00,820 So which content it should show 120 00:06:00,820 --> 00:06:02,830 and how the content should look like, 121 00:06:02,830 --> 00:06:04,460 how it should be styled. 122 00:06:04,460 --> 00:06:06,180 And therefore it's this code, 123 00:06:06,180 --> 00:06:08,680 these browser instructions that's in the end, 124 00:06:08,680 --> 00:06:13,160 sent back by this remote computer in a so-called response 125 00:06:13,160 --> 00:06:16,990 to your browser and the browser then and knows 126 00:06:16,990 --> 00:06:18,840 how to handle these instructions 127 00:06:18,840 --> 00:06:21,440 because these are standardized as well. 128 00:06:21,440 --> 00:06:24,440 The programming languages that can be used for writing 129 00:06:24,440 --> 00:06:26,850 these instructions are standardized 130 00:06:26,850 --> 00:06:30,620 and the browser then will bring something onto the screen. 131 00:06:30,620 --> 00:06:32,550 That's how the web works. 132 00:06:32,550 --> 00:06:36,079 And even though I took some time to describe this process, 133 00:06:36,079 --> 00:06:39,237 this request response cycle, 134 00:06:39,237 --> 00:06:42,760 of course typically only takes a couple of milliseconds. 135 00:06:42,760 --> 00:06:44,810 It's super efficient and fast. 136 00:06:44,810 --> 00:06:49,340 And that's why visiting websites is super fast. 137 00:06:49,340 --> 00:06:50,800 Now on this big picture, 138 00:06:50,800 --> 00:06:53,570 there are two or actually four other terms 139 00:06:53,570 --> 00:06:54,869 that are worth knowing. 140 00:06:54,869 --> 00:06:58,919 We typically call the browser and us using the browser, 141 00:06:58,919 --> 00:07:02,030 the so-called client or front-end. 142 00:07:02,030 --> 00:07:05,920 And we call the remote computer that hosts the website, 143 00:07:05,920 --> 00:07:09,390 so that has this website and sends it back to us. 144 00:07:09,390 --> 00:07:12,710 We call this remote computer, the so-called server, 145 00:07:12,710 --> 00:07:14,670 or the backend, the server, 146 00:07:14,670 --> 00:07:18,810 because this computer serves the website to us, 147 00:07:18,810 --> 00:07:21,630 the client who is requesting the website. 148 00:07:21,630 --> 00:07:24,370 So these are more terms that are worth knowing, 149 00:07:24,370 --> 00:07:27,360 but now this big picture actually takes us 150 00:07:27,360 --> 00:07:29,640 to the next important question. 151 00:07:29,640 --> 00:07:33,140 We need to take a closer look at this response 152 00:07:33,140 --> 00:07:35,010 and these browser instructions, 153 00:07:35,010 --> 00:07:39,410 because that helps us understand which code we need to write 154 00:07:39,410 --> 00:07:41,243 as a web developer, because of course, 155 00:07:41,243 --> 00:07:43,110 that is always important to us, 156 00:07:43,110 --> 00:07:45,150 which kind of code do we need to write 157 00:07:45,150 --> 00:07:48,107 and which programming languages should we use?