Interface of Serach

Search Interface

The search algorithm and search interface are used to find the most relevant document in the index based on the search query. First the search engine tries to determine user intent by looking at the words the searcher typed in.

These terms can be stripped down to their root level (e.g., dropping ing and other suffixes) and checked against a lexical database to see what concepts they represent. Terms that are a near match will help you rank for other similarly related terms. For example, using the word swims could help you rank well for swim or swimming.

Search engines can try to match keyword vectors with each of the specific terms in a query. If the search terms occur near each other frequently, the search engine may understand the phrase as a single unit and return documents related to that phrase.

WordNet is the most popular lexical database. At the end of this chapter there is a link to a Porter Stemmer tool if you need help conceptualizing how stemming works.

Searcher Feedback

Some search engines, such as Google and Yahoo!, have toolbars and systems like Google Search History and My Yahoo!, which collect information about a user. Search engines can also look at recent searches, or what the search process was for similar users, to help determine what concepts a searcher is looking for and what documents are most relevant for the user’s needs.

As people use such a system it takes time to build up a search query history and a click-through profile. That profile could eventually be trusted and used to

•       aid in search personalization

•       collect user feedback to determine how well an algorithm is working

•       help search engines determine if a document is of decent quality (e.g., if many users visit a document and then immediately hit the back button, the search engines may not continue to score that document well for that query).

I have spoken with some MSN search engineers and examined a video about MSN search. Both experiences strongly indicated a belief in the importance of user acceptance. If a high-ranked page never gets clicked on, or if people typically quickly press the back button, that page may get demoted in the search results for that query (and possibly related search queries). In some cases, that may also flag a page or website for manual review.

As people give search engines more feedback and as search engines collect a larger corpus of data, it will become much harder to rank well using only links. The more satisfied users are with your site, the better your site will do as search algorithms continue to advance.

Real-Time versus Prior-to-Query Calculations

In most major search engines, a portion of the relevancy calculations are stored ahead of time. Some of them are calculated in real time.

Some things that are computationally expensive and slow processes, such as calculating overall inter-connectivity (Google calls this PageRank), are done ahead of time.

Many search engines have different data centers, and when updates occur, they roll from one data center to the next. Data centers are placed throughout the world to minimize network lag time. Assuming it is not overloaded or down for maintenance, you will usually get search results from the data centers nearest you. If those data centers are down or if they are experiencing heavy load, your search query might be routed to a different data center.

Search engines such as Google and Yahoo! may update their algorithm dozens of times per month. When you see rapid changes in your rankings, it is usually due to an algorithmic shift, a search index update, or something else outside of your control. SEO is a marathon, not a sprint, and some of the effects take a while to kick in.

Usually, if you change something on a page, it is not reflected in the search results that same day. Linkage data also may take a while to have an effect on search relevancy as search engines need to find the new links before they can evaluate them, and some search algorithms may trust links more as the links age.

The key to SEO is to remember that rankings are always changing, but the more you build legitimate signals of trust and quality, the more often you will come out on top.

The more times a search leads to desired content, the more likely a person is to use that search engine again. If a search engine works well, a person does not just come back, they also tell their friends about it, and they may even download the associated toolbar. The goal of all major search engines is to be relevant. If they are not, they will fade (as many already have).

Search engines make money when people click on the sponsored advertisements. In the search result below you will notice that both Viagra and Levitra are bidding on the term Viagra. The area off to the right displays sponsored advertisements for the term Viagra. Google gets paid whenever a searcher clicks on any of the sponsored listings.

The white area off to the left displays the organic (free) search results. Google does not get paid when people click on these. Google hopes to make it hard for search engine optimizers (like you and I) to manipulate these results to keep relevancy as high as possible and to encourage people to buy ads.

Later in this e-book we will discuss both organic optimization and pay-per-click marketing.