Table of Contents
- What is Web Scraping?
- The Process of Web Scraping
- Applying Web Scraping
- What is Web Crawling?
- The Process of Web Crawling
- Applying Web Crawling
- Relation Between a Scraper and a Crawler
- Resuming Web Scraping vs. Web Crawling
- Final Thoughts
Introduction to Web Crawling vs Web ScrapingSo, what is the difference between web scraping and web crawling? This is a question that business owners who have hired a web data scraping service often ask. And really, many people who are more or less familiar with data scraping can have trouble identifying the difference between these two concepts, because they are kind of similar, and go hand in hand while gathering information online. In this article, we’ll uncover the web scraping meaning along with the web crawling meaning, and point out the key difference to prevent any confusion.
What is Web Scraping?Web scraping, also known as web harvesting, is a process of extracting an enormous amount of information from online sources and storing it in a local or cloud-based data warehouse in SQL, XML, or Excel formats. The bots used in scraping are called scrapers, which extract content based on the given requirements in a short period of time. Though scraping is mostly done in an automated manner, there are cases when it can be done manually.
The Process of Web ScrapingAs we have already noted, web scraping is the de facto extraction of content from online sources. It mainly includes studying the HTML of the page and setting up the scrapers to get content from specified elements of the HTML tree. By using this technique, developers resolve the main issue of scraping – changes to the sites being scraped – for which the scrapers need to be updated correspondingly. So, getting the HTML code first and then scraping the content saves time that would be used fetching the data twice, and fixing only the scrapers. The scraping process is comprised of the following four steps:
- Request the target site.
- Get the requested info in HTML format.
- Parse and extract the response. To put it simply, take the code as text and extract the relevant content.
- Download the content and save it in a CSV or JSON, or in a database to retrieve and use in the future.
Applying Web ScrapingAlmost every type of business, from startups to large enterprises, can use data scraping technology to reach its business goals. So, let’s consider use case examples for how business owners can use it.
Whether for competitor price monitoring or product research, data scraping is applied to collect valuable content and harvest essential insights. Similarly, for e-commerce, countless product descriptions and images are needed. With the help of content harvesting, it is quite possible to get all the necessary information. For online markets, this is the best way to keep up with the rapid changes happening every moment.
What is Web Crawling?The tools used in web crawling are known as web crawlers. So, what is a web crawler and how does it work? A web crawler is a program that automatically crawls across the web by using particular links (URL addresses). Then, after accessing the necessary links, downloading and storing the HTML code for further data extraction, web scraping comes into play.
The Process of Web CrawlingData crawling works in the following steps:
- Take the specific URLs from the crawl frontier;
- Visit all pages corresponding to those URLs;
- Review and categorize web pages;
- Index the data from the URLs found and store it in the database;
- After indexing the target data, crawlers detect outbound links;
- Repeat steps 2-5 until the frontier is empty.
Applying Web CrawlingHave you ever wondered how we got answers to our questions in this digital age? It is really convenient to enter a query into the search bar and get a list of helpful resources to get our answers. This process uses data crawling.
Can you imagine your life without Google? Without web crawling, you wouldn’t be able to get search results from Google in such an effective manner. Every day, search engines crawl 25 billion or more pages to generate the results you are looking for. And, because of ever-changing requests, crawlers have to be adjusted as well. Crawlers screen the pages and also rank the quality of content, and execute many other functions to create the indexing at the end.
As you can see, data crawling is critical in generating accurate results and is the leading part of web scraping.
Relation Between a Scraper and a CrawlerNow we know the answer to the question: “what are web scrapers?” and are able to define web scraping. You also have an idea of how to crawl data from a website and know the web crawler’s meaning. Now, let’s understand how these can be related and once again clarify the difference. If we need info from a particular page, a parser is enough. But in this case, when we need to fetch the URLs to parse them and get the needed content, it is necessary to combine a crawler and a scraper. This procedure starts with a crawler that generates URLs to be scraped, and then a scraper comes into play and parses the information from the pages.
Resuming Web Crawling vs Web ScrapingThis is the point where we emphasize that web crawling and web scraping are connected processes, but they are not the same. Keep in mind the below table to remember the main difference between both concepts and to have an idea of which one will be more suitable for your business.
|Web Scraping||Web Crawling|
|It extracts a specific type of information from the target sites||It accesses the target links to download and store them|
|Is applied for downloading information||Is applied for indexing information|
|It uses scrapers||Uses crawlers or spiders|
|It is performed on both small and large scales||Is mostly used on a large scale|
|A crawler and a parser are needed||Only a crawler is needed|