Web Crawling vs Web Scraping: What's the Difference?

Jan 9, 2024 ยท 3 min read

Web crawling and web scraping are related concepts that both involve automatically traversing or extracting data from websites. However, there are some key differences:

What is Web Crawling?

Web crawlers, also known as spiders or bots, are programs that systematically browse the web in an automated fashion. Their main goal is to discover new web pages and content to be indexed by search engines.

Some examples of popular web crawlers are:

  • Googlebot - Crawls web pages to be included in Google's search index
  • Bingbot - Microsoft's web crawler for Bing search engine
  • Facebook crawler - Extracts metadata from links shared on Facebook
  • Key Functions of Web Crawlers

  • Finds new web pages by following hyperlinks
  • Extracts data like page titles, metadata, links for search engine indexes
  • Checks for changes in existing pages
  • Identifies broken links or 404 errors
  • So in summary, web crawlers focus on the discovery and indexing of web pages rather than the extraction of specific data.

    What is Web Scraping?

    Web scraping refers to extracting data from websites through an automated process. Unlike web crawlers, web scraping focuses on gathering specific information from web pages rather than just discovering new URLs.

    Key Functions of Web Scraping

  • Extracts specific text, data, images from web pages
  • Structures scraped data into a format like a CSV, JSON or a database
  • Used to gather data for analysis from ecommerce sites, social media and more
  • Can bypass CAPTCHAs and access data behind login screens
  • So web scrapers are more specialized data extraction programs compared to standard web crawlers. Popular libraries used for web scraping include BeautifulSoup, Selenium, Scrapy and more.

    Key Differences

    Web CrawlingWeb Scraping
    Discovers new web pages to indexExtracts specific data from web pages
    Focuses on gathering URLs and linksFocuses on gathering textual data, images etc
    Used by search engines for indexingUsed for scraping data for analysis
    Broad coverage of the webNarrow data extraction from specified sites

    FAQ

    Is Google a web crawler or web scraper?

    Google operates the Googlebot web crawler to discover new web pages for its search index. It is not a web scraper.

    Is web scraping illegal?

    Web scraping is generally legal unless explicitly forbidden by a site's terms of service. However, scraping at large scales can be considered data theft or denial of service attacks.

    What are some alternatives to web scraping?

    Some alternatives are using official APIs if available, data partnerships, manually copying data or using services like proxies or web data integration platforms.

    Main Takeaways

  • Web crawlers browse websites broadly to index new pages, while web scrapers extract specific data from sites.
  • Crawlers are used by search engines, scrapers are used for data analysis.
  • Scraping may be illegal if forbidden by terms of service or done at excessively high levels.
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