Currently, the World Wide Web (or the Web for short) is a huge information source. Before the Web, finding information means asking other person or looking for it in some books or other kinds of text document. Now, if we need information about something, we can just open a web browser and search it in web search engine like Google. The Web is also a popular communication media. People interact with each other via web forum or social network web site like Facebook and Twitter. Finally, the Web is also an important channel for conducting business. Many companies have used the Web for product campaign or to open online store.
Because of those important uses of the Web, many researches have been conducted to extract useful information from the Web. According to Liu (2007), web mining aim to discover useful information or knowledge from the web hyperlink structure, page content, and usage data. Based on those primary kinds of data used in the mining process, web mining tasks can be categorized into three types: web structure mining, web content mining and web usage mining.
Web Structure Mining
Web structure mining aims to discover useful knowledge from hyperlinks, which represent the structure of the Web. Hyperlink is a link that exists in a web page and refer to another region in the same web page or another web page. The most popular application of web structure mining is to calculate the importance of web pages. This kind of application is used in Google search engine to order its search results. A web structure mining algorithm, PageRank, is invented by Google founders: Larry Page and Sergey Brin. Web structure mining can also be applied to cluster or classify web pages (Gomes and Gong, 2005).
Web Content Mining
Web content mining extracts or mines useful information or knowledges from web page contents. There are two categories of web content mining: structured data extraction and text mining. The idea of structured data extraction is that many web site display important information retrieved from their database using some fixed templates. We can identify those templates by finding repeated patterns in web pages. Apart from structured data, the Web also contain a huge amount of unstructured text, written in natural language. One of the common tasks in text mining is to extract people's opinions or sentiments expressed in product reviews, forum reviews, social networks and blogs.
Web Usage Mining
Web usage mining aims to capture and model behavioral patterns and profiles of users who interact with a web site. Such patterns can be used to better understand the behaviors of different user segments, to improve the organization and structure of the site, and to create personalized experiences for users by providing dynamic recommendations of products and services. Unlike two previous web mining tasks, the primary data source for web usage mining is web server access log, not the web pages.
Gomes, M. and Gong, Z., 2005, Web Structure Mining: An Introduction, Proceedings of the 2005 IEEE International Conference on Information Acquisition
Liu, B., 2007, Web Data Mining: Exploring Hyperlinks, Contents, and Usage Data, Springer