What Is The Difference Between Web Crawling And Web …
This article will help you match your use case to the correct data collection methodology as well as understanding the key advantages and challenges of each option.
30-Nov-2020
In this article we will discuss:
Web crawling Vs. Web scraping
Common web scraping use cases
What are the advantages of each option?
Main challenges
Web crawling, also known as Indexing is used to index the information on the page using bots also known as crawlers. Crawling is essentially what search engines do. It’s all about viewing a page as a whole and indexing it. When a bot crawls a website, it goes through every page and every link, until the last line of the website, looking for ANY information.
Web Crawlers are basically used by major search engines like Google, Bing, Yahoo, statistical agencies, and large online aggregators. The web crawling process usually captures generic information, whereas web scraping hones in on specific data set snippets.
Web scraping, also known as web data extraction, is similar to web crawling in that it identifies and locates the target data from web pages. The key difference, is that with web scraping, we know the exact data set identifier e. g. an HTML element structure for web pages that are being fixed, from which data needs to be extracted.
Web scraping is an automated way of extracting specific data sets using bots which are also known as ‘scrapers’. Once the desired information is collected it can be used for comparison, verification, and analysis based on a given business’s needs and goals.
Here are some of the most popular ways in which businesses leverage web scraping to attain their business goals:
Research: Data is often an integral part of any research project whether it is purely academic in nature or for marketing, financial, or other business applications. The ability to collect user data in real-time and identify behavioral patterns, for example, can be paramount when trying to stop a global pandemic or identify a specific target audience.
Retail / eCommerce: Companies, especially in the eCom space need to regularly perform market analyses in order to maintain a competitive edge. Relevant data sets that both front and backend retail businesses collect include pricing, reviews, inventory, special offers, and the like.
Brand Protection: Data collection is becoming an integral part of protecting against brand fraud, and brand dilution as well as identifying malicious actors who are illegally profiting from corporate intellectual property (names, logos, item reproductions). Data collection helps companies monitor, identify, and take action against such cybercriminals.
Key web scraping benefits
Highly accurate – Web scrapers help you eliminate human errors from your operations so that you can be confident that the information you receive is 100% accurate.
Cost-efficient– Web scraping can be more cost-effective as more often than not you will need less staff to operate and in many cases, you will be able to gain access to a completely automated solution that requires zero infrastructure on your end.
Pinpointed – Many web scrapers allow you to filter for exactly the data points you are looking for meaning you can decide that on a specific job they collect images and not videos or pricing and not descriptions. This can help you save time, bandwidth, and money over the long term.
Key data crawling benefits
Deep dive – This method involves an in-depth indexation of every target page. This can be useful when trying to uncover and collect information in the deep underbelly of the World Wide Web.
Real-time– Web crawling is preferable for companies looking for a real-time snapshot of their target data sets as they are more easily adaptable to current events.
Quality assurance– Crawlers are better at content quality assessment meaning it is a tool that provides an advantage when performing QA tasks for example.
Despite their difference web crawling and web scraping share some mutual challenges:
#1: Data blockades– Many websites have anti-scraping/crawling policies which can make it challenging to collect the data points you need. A web scraping service can sometimes be extremely effective in this instance especially if they give you access to large proxy networks that can help you collect data using real user IPs and circumvent these types of blocks.
#2: Labor-intensive– Performing data crawling/scraping jobs at scale can be very labor-intensive and time-consuming. Companies who may have started off needing data sets once in a while but now need a regular flow of data, can no longer rely on manual collections.
#3: Collection limitations– Performing data scraping/crawling can usually be easily accomplished for simple target sites but when you start encountering tougher target sites, some IP blocks can be insurmountable.
Summing it up
Now that you know the difference between web crawling and web scraping all you need to do is choose which of them is most effective for your specific use case. You need to determine your budget and whether you have an in-house staff who can manage your data collection process or if you prefer outsourcing this to a data collection network.
Yair Ida | Sales Director Yair is a Sales Director at Bright Data. He specializes as a growth strategist and works in the fields of SaaS business development, sales, and marketing. He is a self-proclaimed ‘data entrepreneur’ with a deep knowledge of software products that he works with in order to help businesses create scalable, efficient, and cost-effective data collection processes.
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Data Crawling vs Data Scraping – The Key Differences
One of our favourite quotes has been, ‘If a problem changes by an order, it becomes a different problem’ and in this lies the answer to – Data Crawling vs Data Scraping.
Data Crawling means dealing with large data sets where you develop your crawlers (or bots) which crawl to the deepest of the web pages. Data scraping, on the other hand, refers to retrieving information from any source (not necessarily the web). It’s more often the case that irrespective of the approaches involved, we refer to extracting data from the web as scraping (or harvesting) and that’s a serious misconception.
Data Crawling vs Data Scraping – Key Differences
1. Scraping data does not necessarily involve the web. Data scraping tools that help in data scraping could refer to extracting information from a local machine, a database. Even if it is from the internet, a mere “Save as” link on the page is also a subset of the data scraping universe. Data crawling, on the other hand, differs immensely in scale as well as in range. Firstly, crawling = web crawling which means on the web, we can only “crawl” data. Programs that perform this incredible job are called crawl agents or bots or spiders (please leave the other spider in spiderman’s world). Some web spiders are algorithmically designed to reach the maximum depth of a page and crawl them iteratively (did we ever say crawl? ). While both seem different, web scraping vs web crawling is mostly the same.
2. The web is an open world and the quintessential practising platform of our right to freedom. Thus a lot of content gets created and then duplicated. For instance, the same blog might be posted on different pages and our spiders don’t understand that. Hence, data de-duplication (affectionately dedup) is an integral part of web data crawling service. This is done to achieve two things — keep our clients happy by not flooding their machines with the same data more than once; and saving our servers some space. However, deduplication is not necessarily a part of web data scraping.
3. One of the most challenging things in the web crawling space is to deal with the coordination of successive crawls. Our spiders have to be polite with the servers, that they do not piss them off when hit. This creates an interesting situation to handle. Over some time, our spiders have to get more intelligent (and not crazy! ). They get to develop learning to know when and how much to hit a server, how to crawl data feeds on its web pages while complying with its politeness policies. While both seem different, web scraping vs web crawling is mostly the same.
4. Finally, different crawl agents are used to crawling different websites and hence you need to ensure they don’t conflict with each other in the process. This situation never arises when you intend to just crawl data.
Data ScrapingData CrawlingInvolves extracting data from varioussources including webRefers to downloading pages from thewebCan be done at any scaleMostly done at a large scaleDeduplication is not necessarily a partDeduplication is an essential partNeeds crawl agent and parserNeeds only crawl agent
On a concluding note, when talking about web scraping vs web crawling. ‘Scraping’ represents a very superficial node of crawling which we call extraction, and that again requires few algorithms and some automation in place.
What Is The Difference Between Web Scraping And Web Crawling? – Zyte
People talk sometimes interchangeably about these two. But, actually, there’s a difference. Want to know what is the difference between web scraping and web crawling? You’re in the right place.
The short answer
The short answer is that web scraping is about extracting the data from one or more websites. While crawling is about finding or discovering URLs or links on the web.
Usually, in web data extraction projects, you need to combine crawling and scraping. So you first crawl – or discover – the URLs, download the HTML files, and then scrape the data from those files. This means you extract data and do something with it, like storing it in a database or further processing it.
Different purposes
Going deeper, there’s a big difference in the purpose of these two things and how they work.
In web scraping, it’s all about the data. The data fields you want to extract from specific websites. And it’s a big difference because with scraping you usually know the target websites, you may not know the specific page URLs, but you know the domains at least.
With crawling, you probably don’t know the specific URLs and you probably don’t know the domains either. And this is the reason you crawl: you want to find the URLs. So that you can do something with them later. For example, search engines crawl the web so they can index pages and display them in the search results.
But another crawling example would be when you have one website that you want to extract data from – in this case you know the domain – but you don’t have the page URLs of that specific website. So you don’t know what pages to scrape. So first you create a crawler that will output all the page URLs that you care about – it can be pages in a specific category on the site or in specific parts of the website. Or maybe the URL needs to contain some kind of word for example and you collect all those URLs – and then you create a scraper that extracts predefined data fields from those pages.
Different outputs
So with web crawling the output is a lot more simple because it’s just a list of URLs — I mean you can have other fields as well but the main elements are the URLs.
And with web scraping, you usually have a lot more fields 5-10-20 or more data fields. The URL can be one, but when you scrape, you extract the data not necessarily for the URL but for other data fields that are displayed on the website which can be – depends on the business use case – product name or product price, or some text or other information from any type of website.
Learn more about web scraping
Here at Zyte (formerly Scrapinghub), we have been in the web scraping industry for 12 years. We have helped extract web data for more than 1, 000 clients ranging from Government Agencies and Fortune 100 companies to early-stage startups and individuals. During this time we gained a tremendous amount of experience and expertise in web data extraction.
Here are some of our best resources if you want to deepen your web scraping knowledge:
Web scraping: Best practicesEnterprise web scraping: A guide to scraping at scaleLegal compliance in web scrapingThe build in-house or outsource decisionPrice intelligence: Everything you need to know about price crawlingPrice intelligence Data knowledge hub
Frequently Asked Questions about web scraping crawling
What is web scraping vs web crawling?
The short answer is that web scraping is about extracting the data from one or more websites. While crawling is about finding or discovering URLs or links on the web. Usually, in web data extraction projects, you need to combine crawling and scraping.
Is web scraping legal?
So is it legal or illegal? Web scraping and crawling aren’t illegal by themselves. After all, you could scrape or crawl your own website, without a hitch. … Big companies use web scrapers for their own gain but also don’t want others to use bots against them.
What is Web crawling used for?
A web crawler, or spider, is a type of bot that is typically operated by search engines like Google and Bing. Their purpose is to index the content of websites all across the Internet so that those websites can appear in search engine results.
