Web scraping and web crawling are both used for data mining, but while a lot of people think they are the same, they are not.
This article will take you through the key differences and which one of the two is useful for you.
Web Crawling
Web crawling is basically what fuels search engines such as Yahoo, Bing, and Google. Web crawlers find and get links from seed URLs. From the starting point, the web crawler will browse website pages, follow links, find new pages, and extract content from the pages in an indiscriminate manner.
Web Scraping
Web scraping has a slight difference from web crawling. It is the process whereby structured information is being extracted from a web page, usually by a means that is specifically crafted for the website. Websites can be scraped without crawling. For instance, if you have a certain list of websites to scrape from.
Web scraping is usually targeted at structured data to collect company names, phone numbers, emails, URLs, and for price comparison. The data extracted can then be parsed, searched and formatted, and stored into a database.
Web scraping and web crawling can carry out different activities to achieve these goals. Crawlers and scrapers might submit forms, execute JavaScript, log in to a website, emulate human users, etc. These two terms are most often used interchangeably, but scraping a website is a much more focused process, whereby specific data is extracted for further processing. This is why web scraping is perfect for someone that wants to scrape data from a source and use it in innovative ways.
Web Scraping Vs. Web Crawling: What Are The Differences?
Here is a comprehensive picture of the significant differences between a scraper and a crawler.
- Web crawling is too generic as compared to specific data scraping
- A scraper works to take and download the target data. All it does is “scrape” data. A crawler, on the other hand, will go through the target data without downloading it.
- Web scraping can be done manually while web crawling requires the use of a crawling agent or a spider bot
- Deduplication isn’t always necessary and can also be done in smaller scales with web scraping. This is because it can be done manually. On the other hand, when it comes to web crawling, a lot of information can be duplicated. To prevent excessive duplicate content, a web crawler will filter out duplicate content.
Web Crawling Vs. Web Scraping: Examples
To know whether what you need is to scrape or to get a crawler, you will need to be educated on what can be done with both scraper and crawler.
Here is how crawling can be used to your advantage.
If you are looking to audit your own website, look for broken links, generally perform some SEO expert magic, you will want to try an SEO crawler such as Screaming Frog. This software will crawl your website, detect 404 errors, find duplicates, analyze your Metadata, and also collect every possible information.
When it comes to web scraping, an example is price intelligence research. For example, I’d you wanted to sell a particular product on eBay, you will have to get the price range of a similar item. This is where scraper comes in. If you are a newbie, Octoparse is the perfect software to scrape. With Octoparse, after the magic is done, you would have a list of products, URLs and product prices. You can also narrow the information for data extraction according to your needs.
Simple. Right?
Bottom Line on Web scraping and Web Crawling
From the article, you would understand that although they are used interchangeably, web scraping and web crawling are two different processes. A crawler will perform its duty by crawling the website like a spider, while a scraper will scrape the target data and download it