How Search Engines Work

It’s an everyday miracle that you can type into a search engine like Google “plumber San Diego,” and the search engine will provide you with page after page of likely plumbing websites that you can click on. How does that happen? How does Google know that these are plumbing websites and that they operate out of San Diego? And how does this long listing of websites show up in fractions of a second?

Search Engines Have Read Everything on Internet Already

It starts with search engines reading every webpage on the Internet long before you ever searched for a plumber. Search engines don’t read the version of the Internet pages that you and I look at. They read another version of each page called the “Source Code.” These pages are written by programmers in a computer-readable language, most often HTML. Here’s how you can see a Source Code version of a webpage. Choose a webpage that has a lot of text on it. Right-click it where there’s no text or image. Then, click on the option “View Source Code” or similar wording.

Search Engine Version of Webpages – Source Code

If you’ve chosen a text-heavy page, you should see blocks of ordinary English text — the same text that appears on the human version, but not as nicely formatted. There will also be symbols and words that you may not recognize. These are HTML or some other computer language. Some of these words and symbols tell the Internet the colors and typefaces to show visitors. Some of these tell search engines more about the content of the page. For example, search engines can’t get an idea of what’s in a photo, so the programmer who wrote the HTML may have labeled a photo “owner of plumbing contracting company.” This gives the search engine more data about what’s on the page.

To return to the usual human view of the page, click the X on the tab at the top of the Source page.

Search Engines Read and Annotate All Webpages

Search engines read every page that’s on the Internet with programs called “robots,” “bots,” or “spiders.” They’re all the same thing. They are considered to “crawl” pages. Bots crawl websites night and day even if they’ve seen it all before. This is because webmasters modify pages, delete pages, and add pages. The search engine will re-read some websites frequently if it’s found that they change often. This might be every few days or, in some cases, every day or even a few times a day. On the other hand, if the search engine has found historically that a website doesn’t change much, it might not get around to re-reading it for weeks.

In addition to reading pages, the search engine makes notes about each page. It notes what words and phrases are on each page. Google has compiled so much information about the words and phrases on pages that it knows the frequency with which every word appears in conjunction with every other word. If I were to do a search on “electrical work,” it might give me electricians’ websites, even ones that don’t include the phrase “electrical work.” The search engine would know that electrician websites are about electrical work simply because the phrase “electrical work” is frequently found on them.

Search engines save every webpage of the Internet plus its annotations in computers that belong to the search engine. These pages are considered to be “indexed” by the search engine. They’re also being stored or “cached.” The reason that the Google search engine can boast about providing searchers with humongous numbers of pages in fractions of a second is that these pages are already in its computers and already indexed. Google already knows what words are on every page and can serve up sites relevant to your search immediately.

Including Keywords on Your Website

It’s clear from this description that if you want a search engine to consider your general contractor website relevant to a search for “general contractor Philadelphia,” it would be desirable to have text featuring the words “general contractor” and “Philadelphia” along with a Philadelphia address. Plus a lot of related words that the search engine already knows should be on a general contractor’s site — like “contracting” “subcontractors” “supervise the job” “construction” “materials” and so on. These words and phrases tell the search engine that it has most likely come across a general contractor’s website in Philadelphia. The most important of these words and phrases, the ones that people most frequently type in when looking for your trade in your city are your main “search terms” or your “keywords.”

It will also be helpful for the contractor’s rankings to have a lot of useful articles for visitors on his website about contracting, home improvement, and related topics. Links to his website are also important. In fact, there are quite a number of factors that determine the rankings of a website on search engines.