Common search engine principles

To understand seo you need to be aware of the architecture of search engines. They all contain the following main components:

Spider - a browser-like program that downloads web pages.

Crawler – a program that automatically follows all of the links on each web page.

Indexer - a program that analyzes web pages downloaded by the spider and the crawler.

Database– storage for downloaded and processed pages.

Results engine – extracts search results from the database.

Web server – a server that is responsible for interaction between the user and other search engine components.

Specific implementations of search mechanisms may differ. For example, the Spider+Crawler+Indexer component group might be implemented as a single program that downloads web pages, analyzes them and then uses their links to find new resources. However, the components listed are inherent to all search engines and the seo principles are the same.

Spider. This program downloads web pages just like a web browser. The difference is that a browser displays the information presented on each page (text, graphics, etc.) while a spider does not have any visual components and works directly with the underlying HTML code of the page. You may already know that there is an option in standard web browsers to view source HTML code.

Crawler. This program finds all links on each page. Its task is to determine where the spider should go either by evaluating the links or according to a predefined list of addresses. The crawler follows these links and tries to find documents not already known to the search engine.

Indexer. This component parses each page and analyzes the various elements, such as text, headers, structural or stylistic features, special HTML tags, etc.

Database. This is the storage area for the data that the search engine downloads and analyzes. Sometimes it is called the index of the search engine.

Results Engine. The results engine ranks pages. It determines which pages best match a user's query and in what order the pages should be listed. This is done according to the ranking algorithms of the search engine. It follows that page rank is a valuable and interesting property and any seo specialist is most interested in it when trying to improve his site search results. In this article, we will discuss the seo factors that influence page rank in some detail.

Web server. The search engine web server usually contains a HTML page with an input field where the user can specify the search query he or she is interested in. The web server is also responsible for displaying search results to the user in the form of an HTML page.

Requirements for a Web Site

Requirements for a Web Site
Documenting Business, Content, Functional and Technical Requirements
Business Requirements Defined: A web site is designed to help a business market themselves and increase sales. Business requirements document the business functions that the web site will support. They do not necessarily document the functions the web site should have, but instead enable an analyst to determine what parts of these business functions can be made available through the web site.

· The process to create product information for the web site
· The process to sell products from start to finish
· The process to order products or materials from suppliers
· Customer service processes

Other business requirements can include items that are not processes but need to be considered during design phases:

· Look and feel standards
· Usability guidelines
· Legal and security guidelines/issues
Content Requirements Defined: All web sites have content. So it’s necessary to capture all the types of content that will be used on the site. For each type of content identify the following:

· What is the purpose of the content? Is it related to any other content?
· Does it exist in web copy today?
· Does it exist in some other format (i.e. Word, xls, PDF, graphic)?
· Who owns it?
· Who maintains and updates it? Is there any workflow associated with it?
· Who is the audience for this content?
· How often is it updated?
· Is this content static, or does it need to be available for only periods of time?
· If the site is bilingual, is the content translated? Does it need to be?
Technical Requirements Defined: In order to ensure the web site will support the number of users who will visit it and ensure the functionality works properly, technical requirements needs to be document such as:

· Expected volumes of users
· Expected peak periods of use
· Types of content that will create high load (like video and audio files)
· Security Requirements (is the site a secure site, rules for passwords)
· Performance Requirements (i.e. page load time)
· Operating availability (i.e. 24/7 availability), including maintenance periods
· Support requirements
· Database Sizes (for storing content)
· Types of Browser to support, including browser resolutions

The more requirements that are defined and documented up front, the more likely the web site will be built properly. By not clearly defining requirements, a web site may not provide the proper functionality or support the volume of users who visit it. The next step is to take these requirements and begin to design an Information Architecture and a Web Site Functional Specification.