How Search Engines Work
Search Engines have been around since 1994 when WebCrawler was launched, and have operated in a similar way since. How they work today has been almost entirely shaped by Google who launched in 1998.
Google now control about 90% of the UK search market, so we have focused on them here.
Search engines are designed to help users find the information they are looking for quickly on the internet. They are able to do that because the internet is essentially a mass of text which can easily be scanned to see which pages have the content most relevant to the users query.
To analyse the whole of the internet for every search query entered would take an extremely long time. To ensure they deliver results to the user quickly, each search engine sends out “crawlers” (also known as “spiders” or “bots”). These are little programmes that run around the internet picking up the key details of each page they crawl through. The information they collect is used to create an “index” which the search engine can easily analyse to bring back a result for the user quickly.
Over the last 10 years search engines have become increasing intelligent so the results they retrieve relate more closely to the initial search query. Rather than bring back results graded on how many times the search term appears on the page, they now:
• Grade different types of content differently.
• Assess the context in which the information is provided.
• Assess how important that page is to that subject.
Google achieve this through two factors:
1. PageRank (Page for “Larry Page” one of the founders, not “webpage”).
2. Hypertext-Matching Analysis.
1. PageRank
Pagerank measures the importance of a web page:• Basically counting the number of other pages linking to the page in question (this can include links from within the same website)
• The worth of each link is calculated based on the PageRank of the page the link comes from
By downloading the Google toolbar you can find out each of your webpages PageRanks.
2. Hypertext-Matching Analysis
This analyses the content of the page and assesses its relevance. In order to do this it looks at everything including:• Text.
• Fonts.
• Where the content is.
• Meta data.
• Subdivisions.
• Content of neighbouring pages.
By combining these two pieces of analysis, Google is able to bring back relevant results.
The whole process is often referred to as the “algorithm” – a very mysterious thing!
All that analysis costs a lot to do and only drives the “free” organic results (the ones on the left hand side) therefore bringing in no income. In order to make money, Google provides the opportunity for advertisers to place “paid for” results on the right hand side of the page.
How Paid Search Works
Pay per click (PPC) was invented by Overture (a part of Yahoo) in 1996. Google were sued for allegedly imitating Overture’s model, and bought a perpetual license in return for shares.Essentially paid search is an auction. The advertiser decides how much they are willing to pay to appear when a keyword is searched on, and which advert they want to appear in that eventuality. Originally the person who was willing to pay the most got the best position on the page.
Nowadays it depends on how much you are willing to pay and on your Quality Score. Your Quality Score varies for every keyword you bid on and is based on the following:
• The click through rate of that keyword.
• How many people click on your advert compared to those who see it.
• The relevancy of your adtext to the keyword it appears for.
• The historical performance of your adwords campaigns.
• How the adwords campaign is structured.
• The relevance of the landing page to the adtext.
• The relevance of the landing page to the keyword.
Search Engine Marketing – SEO & PPC
Search engine marketing covers both SEO (Search Engine Optimisation) and PPC (Pay Per Click):• Search Marketing via SEO relates to making the most of PageRank and HyperText-Matching Analysis to get your website high in the results for selected keywords / keyphrases
• Search Marketing via PPC relates to building and optimising a campaign to put your website in profitable places on the search engines
These are 2 very different methods of achieving search engine success that should be run in tandem so that the results of each can be used to improve the other. The key differences are outlined below:
| SEO | PPC | |
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| Cons |
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If you would like to read more about PPC then please visit our PPC blog
If you would like to read more about SEO then please visit our SEO blog
