The internet is full of information, and the total amount of data is constantly growing.
Anytime you want to know something, you type it in a search bar and receive a list of a few pages out of the trillions existing online.
Have you ever wondered how search engines know where to look? If so, web crawlers are the answer.
Although search engines offer easy access to all the information online, web crawlers play a crucial role in curating the content.
But what is a web crawler, and what technical strategies does it entail? Stick with us to find out!
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What Is a Web Crawler and How Does It Work?
Web crawlers, also known as bots and spiders, crawl the internet for indexing purposes.
Your search engine doesn’t work magically to display the particular websites you need when you’re searching. This specialized program crawls and indexes the websites to deliver the pages for phrases and keywords people look for.
Consider you went grocery shopping. You’d walk into the store and look through several products before purchasing.
Likewise, search engines like Google use web crawlers to help browse the World Wide Web for pages before storing the page information for future searchers.
The search engine crawls websites by moving between the links on the pages. They gather information about the page and store it in the index.
Later, the Google algorithm sorts them out for specific words to collect and rank for users.
In case you want to dive deeper into the topic, read this article: What is a web crawler and how does it work? – Blog | Oxylabs
The Purpose of Web Crawlers
Anyone who wants their website to rank in search engines uses a web crawler. If you do not crawl your website, it would never appear in the search engine – even if you copy an entire paragraph and paste it into the search bar.
Simply put, your website would not exist unless you crawl it.
You must give your website the wings needed to appear in search results and reach the target audience, mainly if you aim to increase the traffic.
Technical Strategies Applied In Web Crawlers
On the surface, web crawlers serve a clear and direct purpose. Nonetheless, they involve several technical strategies to achieve the desired action. These include:
Web Page Acquisition and Analysis
The core idea behind a web crawler is to emulate a web server to make an HTTP request.
Then, the bot uses the HTTP request to send requests to the browser. Once the crawler receives a response from the server, it evaluates and stores the page and completes the work.
Web page parsing is primarily a de-noising technique for web pages. All information on the internet is stored in the form of HTML.
De-noising is about extracting the text of the web content. When the crawler extracts the web page content, it parses the HTML structure to pull out relevant data from the page.
Once spiders access the data, they use two storage techniques: saving the information to the database or storing it in the local file.
Large data is generally saved in the database, whereas a small amount of data can be saved directly to the local file.
This database can utilize the Redis (Remote Dictionary Server) database – a high-performing memory-data structure store used as a key-value database.
This database is characterized by disorganization and no repetition. Every time the bot deals with the page or a URL, it will check whether the Redis database exists.
Also, it may store memory contents on a disk. However, each operation is atomic, ensuring bot authenticity – the spider won’t lose any data due to an unforeseen halt.
Web Search Strategy
The web search strategy has three primary categories.
- The depth-first strategy evaluates the first page before jumping to the next. Nonetheless, one drawback is that the high-value links provided by some portal sites weaken the web pages’ value as it continues to crawl. On top of that, the deeper the crawlers dig, the more problems they can create owing to the complex internet structure.
- The breadth-first strategy is for more generic cases. It allows searching through tree-split levels. So, if the current search is incomplete, it won’t move to the next level. It will explore the whole knowledge area and reduce the efficiency.
- The optimal search strategy detects the similarity between user web pages and target web pages to perform the first crawl. It only analyzes the passed web page for evaluating and predicting. However, it has a downside: it might ignore related web pages during the crawling process.
Case Uses of Web Crawlers
Check out curated some popular use cases of web crawlers below.
People around the globe use web crawlers for collecting information about business competitors or the financial sector. Most importantly, they gather customers’ data and evaluate their habits, wants, and needs through analysis and data mining.
Every time users browse for information on the web, the content’s freshness and relevance are the most critical factors. Crawler collects valuable data, conducts analysis, and obtains pertinent information.
Several secure documents are collected for evaluation to detect which one holds malicious content, identifying the safe ones and forming the feature library. Crawler technology helps test, analyze, and compare the file to the feature library and determine if it’s safe or not.
Perhaps now you know what is a web crawler and what technical strategies it uses. Crawlers sort and filter through web pages to help search engines understand what each page is about.
Though web crawlers have been around for some time now, their potential gained the limelight recently. Today, thousands of businesses use it to gain insight into useful competitor data.