Lesson video

Hi, I'm Allen Heard, your computing teacher, and this is Developing for the Web, lesson four, and this one's all about searching the internet.

You will need a pen for today's lesson, to write some answers down later on, and you will need to turn off any notifications on mobile phones that are nearby so you're not distracted.

You can pause the video until you get the things you need, and when you're ready, we can get started.

Okay, in this lesson, we're going to describe what a search engine is; and we're going to explain how a search engine crawls through the World Wide Web; and we're going to analyse how a search engine ranks and displays results.

Okay, so how do search engines work? Probably use them every day, right? Search engines use keywords and they categorise the pages that they find as they crawl through the World Wide Web.

So when a user wants to find a webpage, they put those keywords in and then the search engine will display hyperlinks to those different webpages that it's found.

Search engines use programmes called crawlers or spiders to find content on the World Wide Web.

These crawlers visit links from one webpage to another, recording common keywords that they find.

By travelling along these links, these crawlers can then find newly created content.

Let's take a look at a Wikipedia page.

So on this one, the source code of the page you explored for meta tags, that explain what the page is about, if you wanted to see the source code of a webpage, you can right click anywhere on a webpage and click view source code.

Important keywords, or headings and words at the top of the page, are seen as more important for search results.

Hyperlinks are then added to the queue to be visited once the search of the page is complete.

When web crawlers finish their searches, the information is stored in a data structure called an index.

Other information is stored too, that may be useful when users run their searches later on.

An index stores information such as frequently used keywords, it may include the types of content that it's found, such as text or images, and it'll also include information of when the page was last updated.

Okay, so task one, you're going to do the job of a web-crawling programme.

So you're going to be given some information for a webpage and you're going to record the content that might be stored if that page was searched, such as the content type, any keywords and the date it was last updated.

So you can pause the video here, use the worksheet and complete the task.

Okay, so here's a possible solution to the webpage that you were given.

There were five keywords that I've picked out from this one, so we've got scratch, right at the top; we've got programming, we've got language, we've got block and we've got Wikipedia.

All of the content that you found was text so, again, we don't have to fill every box in that says text, so we just put text next to that one.

And it did have a last-updated date of the 20th of April 2020.

So now you've had a go at that one, we'll give you another one to try out.

If you didn't get the keywords from the last one, then hopefully, looking at those answers that we've just seen, it might give you a bit of a clue on how to get the answers for this one.

So you've got a second webpage to have a look at.

You can pause the video and complete the task.

Okay, so for crawling this webpage, this one was all about plate tectonics, so they would be my first two main keywords.

We also had Pangea which was the location, with continent, and we had the word world, okay.

On this page, there were two types of content, there were text and there was an image, if you spotted the image tag on that page too, and it was last updated on May 1st, 2019.

So I hope you got all that information from that webpage.

There are potentially millions of pages that could be stored in a search engine index that correspond to a single keyword.

The searches query that index database to find pages with those keywords in them; it's a little bit like finding a needle in a haystack.

Search engine designers create complex algorithms to determine the importance of a webpage beyond the frequency of the keywords that appear.

So how might the following factors be considered when judging the importance of a webpage? Things like when it was last updated, webpages that link to the crawled webpage, other pages that the crawled page links to too, and how long visitors tend to stay on a page.

So if you were to put lots and lots of keywords in your webpage to kind of try and trick people, to drive traffic to your website, then if there were not any useful links to other webpages or it was last updated a long, long time ago, then this page wouldn't be ranked as important as other pages that it found in the search engine index.

Okay, so now we're going to build another webpage and this time, we're going to think about building a quality webpage.

So how might you go ahead and build a quality webpage that would be ranked highly amongst search results? Well, for this page, you're going to need a scenario for the page itself, so your page needs to summarise how search engines work, including how crawlers work, how webpages are indexed, and how webpages could be ranked and why this is necessary.

So that's the kind of information you're going to put on your webpage.

Going to give you some tips; not just going to let you go ahead and create it without any guidance.

Have a clear heading, so make sure you use the h1, h2 tag; we've done that before.

Include keywords regularly near the top of the page, so anything that you feel is key to your information, make sure they're at the top of the page.

Include any meta tags in the head of your page, so again, you saw an example of that in task one, so you'll be able to utilise that information to create some meta tags in there.

Any suitable images, so make sure you're finding some suitable images on the web.

Pixabay is a great place to find images that are copyright free and that you are free to use with your work.

Don't put any junk information in there, anything that's not relevant to the page.

Use complementary colours, so don't use colours that really, really clash and are not easy on the eye, so think about your colours.

And make the key information obvious.

So if you're creating a webpage about how search engines work, make sure that information is front and centre, really clear, really obvious, and not lots of supplementary waffle in there that we don't need.

So you can pause the video and complete the task.

Okay, how did you get along with that? It's a challenging task and I really hope you enjoyed making that HTML page all about search engines and how search engines work.

Obviously I can't look at your work from here, but it'd be great if you could share your work and I'll show you how to do that later on.

So now I've got another task for you.

This is task three, so this is what makes a quality webpage, so just to check to see if you've been taking in what we've been learning during this lesson.

There are some descriptions here.

You've got a worksheet with them on as well.

I'd like you to tick the ones that you think are all part of making a quality webpage.

You can pause the video and complete the task.

Okay, so welcome back.

So here, you can see the ones I've put a cross next to, as far as the ones that make a quality webpage.

So things like using clear headings, using suitable meta tags, important keywords, key information obvious on the page, suitable images, no unnecessary information, and a complementary colour that isn't too strong.

The ones that are not, strictly not part of making a high-quality webpage is putting lots and lots of keywords at the top of your page purely to try and drive traffic to your website; all that's going to do is leave visitors to your page unexcited, disappointed that they've been led to a page that doesn't contain anything that they're after at all.

Links to popular websites that are unrelated to yours, so yes, the crawler would crawl through and find links, and you may think as a designer, well, I've got lots of links to other pages so the crawler's going to populate these links and go searching throughout the internet, but that wouldn't prove very successful because, again, these links wouldn't have any links back to your site and the user would probably, again, be left disappointed.

And as much colour as possible to make it stand out.

Well, I guess, depending on your viewpoint as far as color's concerned, if you've seen some examples of really horrible webpages from the 90s when the internet first came out.

If you haven't, it'd be really good to experience that and have a look at some; they were terrible.

But, yeah, using lots and lots of colours to make it stand out isn't always a good thing; make sure they're complementary colours.

Okay, like I said before, we'd love you to share your work with Oak National.

If you'd like to, please ask your parent or carer to share your work on Instagram, Facebook or Twitter, tagging @OakNational and #LearnwithOak.

See you next time.