WEBVTT 0 00:00.780 --> 00:07.320 Remember a few lectures back when we were discussing the accept-charset attribute, I used the example... 1 00:07.320 --> 00:12.060 of a user writing "theta", the symbol θ into the form. 2 00:12.350 --> 00:12.930 Do you remember that? 3 00:13.380 --> 00:18.840 And I specifically wanted to use theta, because when we use the UTF character encoding type, for example, 4 00:19.350 --> 00:23.130 you can actually see the character θ in the URL address bar. 5 00:23.340 --> 00:31.110 And the only reason this is possible, is because it is part, theta is part, of the extended ASCII character set. 6 00:31.110 --> 00:33.310 Its decimal number is 226... 7 00:33.330 --> 00:36.780 in case you're wondering, which you weren't wondering, I don't even know why I say this stuff. 🤦‍♂️ 8 00:36.960 --> 00:44.130 Anyways, when I was in those lectures, I also mentioned that the URL spec states that only characters... 9 00:44.130 --> 00:51.480 that form part of the ASCII character set, are allowed to be transported in the URL bar. And this means for... 10 00:51.480 --> 00:57.290 characters that are outside of the ASCII character set, that the URL has to be amended in some way. 11 00:57.570 --> 01:01.020 And this is where URL encoding takes place. 12 01:01.050 --> 01:06.960 This is why it has to be there, because we know the ASCII character is very limited in scope. 13 01:07.260 --> 01:14.340 You and I know that a URL, the Uniform Resource Locator, is just an address of a resource on the 14 01:14.340 --> 01:14.610 Web. 15 01:14.820 --> 01:23.130 These URLs, they have a very well defined structure which was originally invented or defined or specked... 16 01:23.130 --> 01:28.250 out, by Tim Burns Lee, the inventor of the World Wide Web. 17 01:28.530 --> 01:36.030 And today, all URLs have to conform, have to follow the rules and syntax rules defined by the 18 01:36.030 --> 01:40.260 W3 Uniform Resource Identifier Specification. 19 01:41.310 --> 01:48.270 That is a mouthful! But all you need to know is that there is this spec, and browsers are obliged to follow... 20 01:48.270 --> 01:48.780 that spec. 21 01:49.080 --> 01:55.980 And in that spec it says that your URLs can only contain a subset of ASCII characters. 22 01:56.220 --> 01:59.220 And this means that many characters are not allowed in the URL. 23 01:59.850 --> 02:03.180 We also have special characters. Like what about spaces, for example? 24 02:03.450 --> 02:07.080 Well, that's exactly why we have URL encoding. 25 02:07.290 --> 02:11.940 And with these special characters, like spaces, what normally happens is that there's a token value... 26 02:11.940 --> 02:15.660 that's used, a percentage sign, followed by two characters. 27 02:15.660 --> 02:19.920 And these two characters correspond to the ASCII character hex value. 28 02:20.130 --> 02:23.100 For example, a space is converted to %20. 29 02:23.250 --> 02:28.380 An exclamation mark is converted to %21, and so on and so forth. 30 02:28.530 --> 02:30.500 So how do you and I encode all these values? Well... 31 02:30.510 --> 02:35.580 the good news is, my dear student, is the browser does this automatically, straight out of the box. 📦 32 02:35.910 --> 02:37.590 Let me hop over to the computer, and show you. 33 02:38.340 --> 02:39.000 So here we go. 34 02:39.000 --> 02:40.050 We're just in Chrome. 35 02:40.050 --> 02:46.410 And if I go to the URL address bar, and let's just type "gerald the giraffe". 36 02:47.750 --> 02:48.290 That's all I've done. 37 02:48.910 --> 02:52.810 What's going to happen when we press the enter or return key? Well, let's do it. 38 02:55.330 --> 03:01.780 You can see that the URL has automatically encoded those special characters, those spaces that I 39 03:01.780 --> 03:02.170 typed. 40 03:02.710 --> 03:06.220 Can you see it? We've got these plus + signs. 41 03:06.730 --> 03:10.510 And don't worry, I know I just said that spaces are converted to %20's. 42 03:11.200 --> 03:12.160 Why is it a plus? 43 03:12.190 --> 03:13.750 Well, that's just a nuance... 44 03:13.750 --> 03:15.340 and we're going to get into that a bit later. 45 03:15.490 --> 03:21.820 But for now, just know that the URL encoding happens automatically by the browser, whether or not you 46 03:21.820 --> 03:22.840 and I like it. 47 03:24.360 --> 03:26.990 Hope that's making sense, and I'll see you in the next lecture.