Web Crawling vs. Web Scraping: Understanding the Distinctions

With the world generating 1.145 trillion MB of data daily, humans can't analyze and structure it alone. This is where data processes help. 

Web scraping and web crawling are methods of gathering data over the Internet. While both terms are used interchangeably, these two approaches are very different. 

Continue reading to discover the difference between web scraping and web crawling and which method suits your data-gathering projects.

Web Crawling and Web Scraping: Are They Different?

Web scraping and web crawling are two different data extraction activities. However, they usually overlap—so it's easy to interchange these terms.

Website crawling involves gathering URLs from web pages for indexing and archiving. This process is usually automated using web crawler agents or “spiders.”

Meanwhile, web scraping involves collecting specific data sets from web pages. It's not limited to URLs.

Take a look at each method to see the distinction between the two processes:

To gain a better understanding of their differences, you must grasp what each process means and how they work. Read on.

Defining Web Crawling 

To crawl the Internet means visiting URLs through hyperlinks. It also means reading the web pages’ meta tags or content for proper indexing.

The best web crawlers worldwide are popular search engines like Google and Bing. They also have the best web crawling architecture.

You can summarize the web or data crawling process in these four steps:

Step 1: Inputting URLs - The web crawler API requires URLs to crawl the web.

Step 2: Visiting All Linked Web Pages - The web crawler API or software visits all pages linked to the starting URLs.

Step 3: Classifying the Web Pages - The web crawler categorizes the web pages according to their meta tags and content.

Step 4: Indexing and Storing the Collected Data - Upon getting the needed data, the tool will index and store it.

What is Web Scraping?

Web scraping is the process of extracting various data sets from websites. It can be small or large scale, depending on the goals of a scraping project. 

Automatic web scraping is more common today than manual "copy/paste." However, manually collecting data from web pages can still work for smaller projects.

Here is a summary of how the web scraping process works:

Step 1: Sending the Request - The web scraper sends a request to the target site.

Step 2: Receiving the Requested Data - The web scraper receives the requested site in HTML.

Step 3: Parsing the Data - The web scraper parses the HTML content to extract a specific data set.

Step 4: Storing the Data - The web scraper stores the data in a readable format for further analysis. Some of these formats are JSON, XML, and spreadsheets.

Screen Scraping vs. API

Screen scraping is a form of web scraping. It gathers data by capturing the user’s screen—typically with the user’s consent.

Financial services usually use this to collect and assess user data. It's also ideal for managing customer bank accounts.

APIs gradually replaced screen scraping due to privacy and security concerns. Another reason was screen scraping takes more work to maintain.  

Banking institutions now provide APIs for transferring data without accessing customer accounts.

Key Differences Between Web Crawling and Web Scraping

The distinctions between web crawling and web scraping lie in their scope, components, goals, and legal concerns. Here is an overview of the key differences between the two:

Take a look at how the two processes differ in particular aspects to gain more insight.

Scope

Web crawling projects are usually large-scale, as seen in search engines. However, it can also be smaller if the project integrates it into a web scraping project.

Meanwhile, web scraping can be small-scale or large-scale, depending on the target data set. Manual data collection from a few web pages can even be web scraping if it can extract the target data.

Goals

Web crawling indexes web pages by following and collecting URLs from hyperlinks. This data may also include metadata for classification purposes.

Web scrapers extract specific data sets and can be “anything.” It is also unnecessary for a web scraper to follow all the links related to a website.

Components

Web crawlers perform their tasks by sending requests to their target URLs. Some web crawlers do it by emulating a regular browser. Otherwise, servers can block them due to bot-like behaviors.

Crawlers also use a link extractor and hypertext analyzer to collect the URLs and analyze meta information.

Most web scrapers also have “web crawlers.” These tools must send requests and identify the target web pages (if they haven't already).

Web scrapers also include data parsing to extract the target data set and filter out irrelevant data. Data parsers transform unprocessed data into a readable format, making it ready to use anytime.

Legality

Web scraping and web crawling are not illegal. However, the legality of these activities depends on the type of data it scrapes or crawls.

In web scraping, it's legal to scrape publicly available information. The activity must follow the target website's robot.txt file to avoid legal issues. The same principle also applies to web crawling. 

Use Cases and Applications 

Web scraping and crawling can go hand-in-hand, but each process has specific use cases.

Here are the everyday use cases of web scraping:

1. Gathering E-commerce Data

Web scraping collects data for market analysis and competitive research. In this case, the usual scraped data sets are prices, descriptions, reviews, offers, etc.

2. Researching the Web

This use case is for business purposes or purely academic. No matter the industry, the Internet is an excellent resource of valuable data.

3. Generating Leads

There are a lot of valuable tools for lead generation. Most of them use web scraping methods to extract data from potential clients.

Meanwhile, web crawling is commonly used for the following:

4. Indexing for Search Engines

Search engines are the most prominent web crawlers on the Internet. They crawl sites and pages, read their content, and index them for web searches.

5. Finding Broken Links

This process is manually doable. However, it can be more efficient and faster by using web crawling tools and techniques.

6. Identifying Target Web Pages For Scraping

This application is where web crawling and web scraping overlap. A web scraper tool uses “crawling” methods to identify the specific URLs with the needed data set.

Advantages and Limitations 

Both processes share some benefits, while some advantages are exclusive for each one. 

Benefits of Web Crawlers/Scrapers

To start up, here are the benefits of web crawling/scraping.

1. Cost and time efficiency

People who say web crawling/scraping usually refer to automated methods. These methods include web scraping APIs, crawling bots, and more. 

They save much time and resources compared to manual research techniques.

2. Accuracy

Web crawling/scraping tools are becoming more accurate. As a result, they reduce the risk of human error—leading to a higher quality of data. 

3. Depth and comprehensiveness

Powerful web crawling/scraping tools can achieve a depth and comprehensiveness that humans can't do. This is crucial in keeping up with today's demand for information.

4. Timely information

Outdated information is still valuable for historical analysis. However, an updated data set is crucial for any business to adapt to significant changes.

Scraping and crawling tools can gather real-time data. Moreover, they can capture data differences every minute.

Challenges in Web Crawling/Scraping Activities

Web crawlers and scrapers are legal, but websites do not welcome them with open arms for a good reason. Here are some of the challenges of these activities:

1. Anti-crawler/scraper tools

Anti-crawler/scraper tools detect and block scraping or crawling activities. Scrapers/crawlers are often unwelcome due to the strain they cause on web servers.

Some sites are challenging to scrape or crawl, even though their data are “public.”

2. IP blocking and CAPTCHA tests

IP blocking and CAPTCHA tests are unavoidable when conducting scraping/crawling activities. 

You can solve this issue by using proxies. However, these proxies are a temporary fix as they will also be blocked eventually.

3. The robot.txt file

Rather than a challenge, it is more of a matter of legal responsibility. If the site owners do not allow crawling or scraping, it is better to comply and find an alternative.

Conclusion

Web crawling and web scraping activities overlap, but they are entirely separate concepts. 

Learning the differences between the two approaches will help you decide which method suits your project, what data you need, and what to do with the data after collecting.