Web Scraping

What Does Web Scraping Mean?

Web scraping is the process of extracting data from a specific web page. It involves making an HTTP request to a website’s server, downloading the page’s HTML and parsing it to extract the desired data.

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Web scraping is used for a variety of purposes, including:

  • Crawling and indexing websites for search engines.
  • Collecting data for market research or competitor analysis.
  • Populating news feeds.
  • Extracting data to train machine learning models.

Web scraping can be done manually, but if the process involves a large number of web pages, it is more efficient to use an automated web scraping tool like BeautifulSoup or Scrapy.

Web scraping may also be referred to as screen scraping, Web harvesting or Web data extraction.

Techopedia Explains Web Scraping

Web scraping is an efficient way to retrieve information that has been posted on websites.

Web scraping can be executed manually or programmatically. Manual scraping is a useful approach for quick and simple data extraction tasks. Automated web scraping is better suited for large extraction tasks, but because it can put a significant load on website servers, some sites may block or limit the rate at which automated scraping tools can send requests.

How Does Manual Web Scraping Work?

Manual web scraping involves using a web browser’s developer tools to view and extract a web page’s source code.

Here are the basic steps:

  1. Open the targeted web page in a browser.
  2. Right-click on the page to open the browser’s developer tools.
  3. View the page’s source code.
  4. Use the browser’s inspector to see which elements correspond to the desired data on the web page.
  5. Copy the desired data.
  6. Paste the data into a text file and save for future use.

How Does Automated Web Scraping Work?

Automated web scraping involves using scraping tools like Python scripts or Scrapy libraries to extract content from multiple web pages.

Here are the basic steps:

  1. The scraping tool programmatically sends HTTP requests to the servers hosting the targeted web pages.
  2. The servers return the HTML source code for the targeted pages.
  3. The scraping tool parses the HTML and extracts the desired data.
  4. The extracted data is saved for further analysis or processing.

Some automated web scraping tools also provide advanced features, such as the ability to handle cookies or get around a site’s Terms of Use that prohibits or limits content scraping.

What is Web Scraping Used For?

Web scraping is used for a variety of business purposes, including:

Data collection — collect data from multiple websites for market research and competitor analysis.

Content aggregation — gather information about content from multiple sources to populate a news feed.

Search engine indexing — crawl and index websites so end users can find information online.

Machine learning — build training datasets for machine learning models.

Price monitoring — monitor price changes on e-commerce websites.

Lead generation — collect corporate contact information, including email addresses and phone numbers.

In general, web scraping is legal as long as it is done for legitimate reasons that don’t violate copyright laws, licensing agreements or a website’s Terms of Use.

Ultimately, the legality of web scraping depends on the purpose of the scraping, the data that’s being accessed, the site’s Terms of Use and the legislation for data sovereignty in the nation-state where the scraping takes place.

How Can I Prevent My Website’s Content From Being Scraped?

Preventing website content from being scraped can be a challenging task because the process is so used widely for legitimate purposes, including search engine optimization (SEO). To reduce the risk of a site’s content being scraped for unauthorized or illegal purposes, publishers can use:

  • Robots.txt files — let web crawlers and scrapers know which web pages are allowed to be accessed and scraped.
  • CAPTCHAs — block undesirable scraper tools by implementing tests that are easy for humans to solve but difficult for computer programs to solve.
  • Request Limits — use rules that limit the rate at which a scraper can send HTTP requests to a website.
  • Obfuscation — transform JavaScript into code that is hard to read and understand by using techniques such as minification, renaming variables and functions or encoding.
  • IP blocking — monitor server logs for scraper activity and block IP addresses for suspected scrapers.
  • Legal action — file a complaint with the hosting provider or seek a court order to stop unwanted scraping.

It’s worth noting that no single solution will completely prevent a website from being scraped. The best approach is often a combination of different techniques.

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Margaret Rouse

Margaret is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical business audience. Over the past twenty years, her IT definitions have been published by Que in an encyclopedia of technology terms and cited in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine, and Discovery Magazine. She joined Techopedia in 2011. Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages.