Here I am describing what is web scraping and it is illegal or not.
What is web scraping : In simple word web scraping means collect information from across the Internet.application that processes the HTML of a web page to extract data for manipulation such as converting the Web page to another format. With web scraping scripts you can connect to a Web page and request a page, exactly as a browser would do. The web server will send back the page which you can then manipulate or extract specific information from. for example suppose http://www.xyz123.com is one website which have some persons contact information’s such as emailid, contact no, address etc. and I am extracting these details(copying these details for my own use) using some scripts this is called scraping.
Types of web scrapping techniques : following are some techniques of web scraping :
A) Copy-and-paste : This is simple human’s manual examination and copy-and-paste based scraping. in some complex scraping issue this may be the only workable solution.
B) Regular expression : Regular Expressions is a language for extracting small bits of text from a larger texts.
C) HTTP Programming : this type of scrapping are using socket programming. HTTP requests to the remote web server.
D) HTML Scraping : this method are use html programming to scrap the web page information’s.
E) DOM Scraping : This technique also known as browser based scraping.
F) Scraping Software’s : Now days many scraping software’s are available online.
Scraping Legality : it depends on data being scraped from internet. if the scraped data is copyright protected it is advice to follow the terms or take the site owner permission first. This link what it means to copyright a website give information about copyright.