Browse through the search engines on a particular topic and you are sure to find a number of articles on a particular topic. Although, the content in many of the data sources is same, they are presented in different styles. This makes them appear different. Hence the comparison of data becomes difficult. Data extraction is a method of retrieving the unstructured data from data sources i.e. different web pages and converting them to structured records for easier comparison of data.

Imagine going through all the websites, copying data and pasting it in a separate document. The task seems quite hectic which nobody would love to do. To make this task easier, a number of data extraction services are available. The use of data extraction tools save time as well as reduces the manual work.

Web scraping or web extraction is a process of data extraction from the html pages of web sites. Web scraping normally involves crawling through the different web pages, capturing the unstructured data and converting them into structured data which can be saved as a record. Web scraping can be considered as simulating a human web browser using the computer software. Web scraping is also known as data mining.

Web extraction is extremely useful for comparison of data from different sources. They are used for online price comparison of a particular product from different sites, weather comparison and monitoring, comparison of real estate data, job postings, collecting phone numbers, capturing the addresses etc. Web scraping tools complete the task with more accuracy and efficiency. The web extraction or web scraping tool does the job very fast while a real human would take a very long time for the sane work. Web scraping tools take nearly 1/6th of the time a real human would take to do the same kind of work.

Web extraction tool is nothing but a software program or a script written to crawl through the web pages, capture the unstructured or semi structured data or information from the web pages and convert them into structured information for storage. The web scraping tools are programmed the way a human would browse through the web pages by entering the website address, visit different web pages and collect the information. The web extraction tools connect to a website and request web pages. The server in turn acknowledges the request and sends the HTML pages. The web extraction program then captures the data from the pages.

Web data extraction is one of the very important tools for World Wide Web. The web data extraction makes it possible to compare different web content which is necessary for a wide range of applications.