Web crawling is essentially the first step of data scraping and helps make the operation more organized and efficient. The web crawler, also known as a crawling spider, crawls and navigates different data sources searching for related URLs that would later be scraped for useful data. But it is not uncommon to find websites blocking crawlers as they are often recognized as bots. And once they can be blocked, crawling would stop, and data extraction would be impeded.
In this article, we discuss the importance of web crawlers, the challenges they face, and how to crawl a website without getting blocked.
What Are Web Crawlers?
A web crawler can be defined as a bot used for downloading and indexing URLs and related links. The goal is to gather these links sequentially for eventual scrapping. In this regard, web crawlers are known to precede web scrapers making the process of data extraction smoother and faster. They are more popularly used by search engines, where they are used to crawl websites and learn their content to allow for proper indexing and ranking.
However, they are now being used by companies to navigate websites and collect links that will be scrapped. Web crawlers may be simple – collecting only the links on each webpage, or sophisticated – collecting links and moving from URL to URL and from website to website looking for related links. This is much easier than simply guessing a URL and scraping it, hoping it contains the data you need. Web crawlers perform their activities based on the following criteria:
- Relative Importance of Web Pages
It is impossible to go through all the websites and webpages on the internet as there are billions of them.
Since the idea of crawling is to make the job more effective, crawlers focus on navigating only the websites and web pages that are important to the topic at hand.
- Revisiting Websites
All active websites get updated with new information and content regularly. Web crawlers also function by revisiting websites and webpages and collecting the newest information added.
- Checking Robots.txt file
To better understand how to perform, crawlers also usually check on the requirements in the Robots.txt file on each website.
These contain detailed information and guidelines on how a website should be crawled and whether or not it allows crawling.
Importance of Web Crawlers
Web crawling is important for several reasons, and below are some of the most common:
- Social Media Monitoring
As a part of web scraping, web crawling can monitor what people are saying about a brand on the internet.
Crawlers can be used to navigate different forums, platforms, and channels to gather reviews and feedback.
- Competitor Monitoring
Crawlers can also be used to closely monitor the competitor by targeting what they do on their websites.
This can be used to target how they promote their products and services, for instance. The information gathered can be analyzed and then used to do better.
- Lead Generation
No business can survive on an empty list of leads. Leads are potential subscribers or buyers that brands must have to work on until they become willing to patronize.
Generating this lead involves gathering data from different websites and platforms, and the operation is often done using web crawlers.
- Supply Availability and Pricing
Retailers and smaller brands have to constantly monitor production to determine when certain products are available.
This helps the brands know when to order these products to stay in business. Web crawlers help businesses monitor manufacturers so that they never miss out effectively.
In the same view, crawling can check for prices of similar products across different spaces to help the retailer decide on a suitable and profitable price.
Vital Challenges of Web Crawling and How to Avoid Them
But web crawling, like all other internet activities, is not automatically a smooth and easy process. It is loaded with several challenges, as we will see below:
- IP Ban
Web crawling is often done using any internet-enabled device. This device uses IP to connect to the target websites.
In some cases, these websites can implement measures that read and block IPs, thereby terminating the crawling process.
- Constant Changes In Website Structures
To keep up with the advancing technologies, websites need to continue to make regular changes.
However, these changes can spell doom for crawlers that are not built to adapt easily. A crawler built to crawl only a particular type of website would crash once that structure is changed.
Another very common challenge that people face during web crawling is restrictions. Geo-restrictions are usually implemented to stop traffic and connections from certain websites.
It means that bots originating from those locations cannot successfully carry out crawling.
How to Avoid These Challenges
The options below are valid, and anyone looking for how to crawl a website without getting blocked can use them:
- Using Proxies
A large bulk of people’s problems while crawling can be mitigated by simply using proper proxies.
Proxies do not only offer security and anonymity, but they also help to bypass crawling challenges easily.
- Rotating Proxies
Rotating proxies regularly switch between IPs and locations to avoid repeating the same details.
By rotating these details, websites have difficulty telling if it is the same user making another request.
Also, rotating proxies enable bypassing issues tied to a particular location by simply choosing a different location.
- Changing Crawling Patterns
Websites and servers can also study crawling patterns and use certain algorithms to block a device that has been repeating a known pattern.
Users can easily bypass certain challenges and blocks by changing how they crawl from time to time.
Crawlers help to make data available when combined with web scraping. They search, and index hyperlinks and URLs later scrapped for useful data.
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