How do search engines work? | SEO for beginners

By | March 4, 2020


To understand what SEO,
short for “search engine optimization”, is, we have to take a look
at what search engines do first. In this video, we are going to talk about how search engines get the information
they need to make their lists of results. So, let’s take a look
at some of the search engines. Of course, there’s Google. Google is the market leader
in search engines, with a reported global market share
of 90% in 2019. There’s also Bing,
which is mostly popular in the States. About 6% of American searchers
choose Bing. Also, about 4% of them uses Yahoo. Russian searchers are much more likely
to use Yandex, which accounts for 45%
of Russian search traffic. And Baidu takes the lead in China,
with a 65% market share. Some users might use
a more privacy-oriented search engine, such as DuckduckGo, or Startpage. And these are just a pick of the bunch. In the reading materials
you can find a link to a tool to help keep track
of these numbers if you want to. Research your audience to discover which
search engine they might be inclined to use. Of course, in a lot of countries, Google is
the default choice of search engine. But, this might not be the case everywhere. So, how do these search engines
get their results? Search engines consist of three parts: 1. the crawler, which is also called
a spider or a bot; 2. the index; and 3. the algorithm. The process begins with a spider. – In this example, we’ll call it a spider, because that’s the easiest image
to remember – A spider travels the web through links. Links connect pages to each other. The spider then looks for data, kind of like a field researcher who sails out
to travel the world looking for knowledge. It particularly looks for content, headings
and links, which contain information about what a page is about,
and how it’s structured. The spider goes around the internet 24/7. When it passes through a website, it saves the HTML version of a page
in an enormous database, and this database is called the index. The spider also finds and indexes
news items, images, and videos for the search engine
to embed in the search results. The index is updated every time
the spider comes round again and finds new information. In Google’s case, the spider revisits
your site more or less often, depending on how often you change things
and how important Google thinks your site is. So now the contents of the page
have been put into the index! But how does that translate to ranking? Search engines use an algorithm for this. The algorithm takes the data
from the index and makes a calculation
on a bunch of factors that predict whether a result will be useful
for the searcher. Then it uses the calculation to see which order of pages the search
engine results page should show. The search engine results page, or SERP, is simply the webpage
where the results are shown. Like when you use Google
to find out more about delicious popcorn. We know the most important elements
the algorithm takes into account because of our experience with SEO,
and researching, and reading about what Google says
about their algorithm. For example, we know that site speed,
great content and the security of sites are important, amongst many others. But Google makes minor changes to the
importance of all these different factors almost every day. They also release bigger updates
every few months. These changes depend on what Google
thinks best serves their users. We’ll tell you more about what
the algorithm looks for in a later video. Also, you can learn more about
some of the big algorithm updates Google released in the past
in our reading materials. But how do you get your website indexed
to be shown by the search engine? Well, spiders need to land on your page
from another link. If there is no link,
the spiders won’t know your site exists. This means that if you launch a new website,
it won’t be spidered immediately. First, an indexed site needs to establish
a link to one of your pages. You can think of the indexed sites
as a network like this. The spiders need a road to the new site
in order to reach and index it. There! Now it’s part of the system! But then, is everything a done deal after
your site is indexed for the first time? No! Spiders follow all the links on the web
that they have access to continuously. This way they can find new sites to index
and change outdated information. Like we maintain our websites
to stay relevant, Google never stops reevaluating
their indexing database and algorithm. While we’re talking about links, both internal links – which are links
from one part of your website to another part of your website – and external links – which are links
from a different website to yours – have a tremendous effect
on search engine rankings. This effect can be positive or negative,
depending on how much sense it makes. For example, a page about baking delicious
cakes linking to a page about cement does not make any sense. Linking to a page about different flavors
of cake frosting matches the subject. We will tell you more about the effects
of linking in the lesson about site structure. In conclusion, these are
our key takeaways for this video: 1. Search engines consist of crawlers
– which are also called spiders or bots – and an index, and an algorithm. 2. Spiders follow links to collect info
about websites, which they put in an index. Search engines then use an algorithm
to turn the index contents into search results. And 3. A spider needs a link from another
website to yours to be able to find it. OK, so now you know a bit more
about how search engines work! In the next video, we’re going to show you an array of different types
of search result snippets that show up on the search engine results
page, and discuss their purpose.

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