The Internet has become the primary source of information for the majority of consumers. Keywords and phrases are typed into a search engine on a computer or mobile device, and a vast volume of related content is presented to the consumer.

Studies suggest that when using search engines, most people do not go beyond the listings mentioned on the first couple of pages of the search engine results list. It has been noted that 90 percent of all users do not look past the first thirty results. This means a high-ranking website has a much higher probability of getting traffic from search engines than a lower ranking website.

Search Engine Optimization involves a number of activities and initiatives that businesses can implement to achieve high search engine rankings. Such activities address both on-page and off-page ranking factors that can affect a website’s or web page’s search engine rankings for specific search terms, resulting in a high placement in a search engine’s “organic,” or “natural,” or “unpaid” search results.

Most search engines can be divided into two common groups:

1. Spider- or Crawler-Based Search Engines

This refers to an Internet-based tool that searches the index of documents or web pages for a particular term, phrase, or text specified by the user, and produces results that are collected, sorted, and automatically indexed based on a defined algorithm.

A software program known as a “robot,” “spider,” or “crawler” scans web pages, follows links between pages and sites, collects information about websites, and indexes this information. This index is a large database of all the websites the crawler has scanned. When a search is performed using a spider-based search engine, the results are provided based on the information in the search engine’s index.

To rank high in search engine results, businesses need to optimize their websites and web pages to ensure that they are being properly indexed by the search engines. Several activities can be initiated in order to influence the information gathered and indexed by robots, spiders, or crawlers. There are many crawler- or spider-based search engines available on the Internet. Some of the popular search engines are Google, Baidu, Bing, and Yahoo.

When a search is performed in a spider-based search engine, the results show both unpaid “organic” listings and paid listings, if any, for the keyword searched. Search engine optimization affects only organic search results. Paid or “sponsored” search results are not affected by SEO. Sponsored results are ads purchased through search engine services such as Google AdWords or Bing Ads. These figures show the anatomy of Google and Bing search engine results.

2.  Human-Edited Web Directories

These directories are Internet search tools that search for information by subject categories. Rather than “robots” or “spiders,” which create directories automatically, human editors create these web directories. A short description along with the URL of the website is submitted to the directory for approval. The search directory then assigns the website to a category enabling the URL to display in search results for that category.

With web directories, the HTML page coding and content of the website seldom directly affect the listing. Directories often provide more targeted results than spider-based search engines. Some examples of popular human-edited web directories for businesses include Dmoz, Business.com, Best of the Web Directory, and Starting Point Directory.

For SEO purposes, a website should be optimized to gain high ranking in spider-based search engines. However, listings of the website in human-edited web directories also help in the overall SEO ranking.