Scrape and Get main content of any web site

Question

I want to scrape web page an get title and main content of any web site. i see this. if you copy any url (for example copy http://en-maktoob.news.yahoo.com/pakistani-army-fuels-anger-securing-swat-taliban-025337458.html to textbox and press enter) from any article this web page get title and article and summarize it. it's work for the most websites. i want to know how is work without using html tag parsing for any website? how get main article of each webpage?