HubSpot: What is a web crawler? (In 50 words or less)

When it comes to technical SEO, it can be difficult to understand how it all works. But it is important to gain as much knowledge as possible to optimize our websites and reach a wider audience. One tool that plays an important role in search engine optimization is none other than the web crawler.

In this article, we will learn what web crawlers are, how they work, and why they should crawl your site.

What is a web crawler

A crawler – also known as a web spider – is a bot that searches and indexes content on the Internet. Essentially, web crawlers are responsible for understanding the content of a web page so that they can retrieve it when a request is made.

You may be wondering, “Who is running these crawlers?”

Usually web crawlers are operated by search engines with their own algorithms. The algorithm will tell the web crawler how to find relevant information in response to a search query.

A web spider will search (crawl) and categorize all of the web pages on the Internet that it can find and are asked to index. So you can tell a web crawler not to crawl your web page if you don’t want it to be found on search engines.

To do this, you need to upload a robots.txt file. Essentially, a robots.txt file will tell a search engine how to crawl and index your site’s pages.

For example, let’s take a look at

Nike used its robot.txt file to determine which links on its website would be crawled and indexed.

In this part of the record, he determined that:

  • Baiduspider web crawler was allowed to crawl the first seven links

  • Baiduspider web crawler was not allowed to crawl the remaining three links

This is beneficial to Nike because some company pages are not intended to be searched and unauthorized links will not affect its optimized pages which help them rank in search engines.

Now that we know what web crawlers are, how do they do their job? Below, let’s review how web crawlers work.

How do crawlers work?

A web crawler works by discovering URLs and examining and categorizing web pages. Along the way, they find hyperlinks to other web pages and add them to the list of pages to explore next. Web crawlers are smart and can determine the importance of each webpage.

A search engine’s web crawler is unlikely to crawl the entire Internet. Rather, it will decide the importance of each web page based on factors such as the number of other pages linking to that page, page views, and even brand authority. Thus, a web crawler will determine which pages to crawl, in what order to crawl them, and how often they should crawl for updates.

Source of images

For example, if you have a new web page or if changes have been made to an existing page, the crawler will take note and update the index. Or, if you have a new web page, you can ask search engines to crawl your site.

When the web crawler is on your page, it examines the copy and meta tags, stores this information, and indexes it for Google to sort by keywords.

Before this whole process is started, the crawler will look at your robots.txt file to see which pages to crawl, which is why it’s so important for technical SEO.

Ultimately, when a web crawler crawls your page, it decides whether your page will show up on the search results page for a query. It is important to note that some web crawlers may behave differently than others. For example, some may use different factors to decide which web pages are most important to explore.

Now that we’ve seen how web crawlers work, let’s explain why they should crawl your website.

Why is website crawling important?

If you want your website to rank in search engines, it needs to be indexed. Without a crawler, your website will not be found even if you search on a paragraph directly taken from your website.

In a simple sense, your website cannot be found organically unless it is crawled once.

To find and discover links on the web through search engines, you need to give your site the opportunity to reach its intended audience by having it crawl – especially if you want to increase your organic traffic.

If the technical aspect of this is confusing, I understand. That’s why HubSpot offers a website optimization course that presents technical topics in simple language and teaches you how to implement your own solutions or discuss them with your web expert.

How and why to crawl your site

If your site has errors that make it hard to crawl, it could drop in SERP rankings. You work hard on your business and your content, but – as mentioned above – no one will know how awesome your site is if they can’t find it online.

Luckily, there are crawling tools like Screaming Frog and Deepcrawl that can shed some light on the health of your website. Performing a site audit with a crawler tool can help you find common errors and identify issues such as:

  • Broken links: When links point to a page that no longer exists, it not only provides a bad user experience, but it can also hurt your ranking in the SERPs.

  • Duplicate content: Duplicate content on different URLs makes it difficult for Google (or other search engines) to choose the most relevant version for a user’s search query. One option to fix this is to combine them using a 301 redirect.

  • Page titles: Duplicate, missing, too long, or too short title tags all affect your page rankings.

Source of images

You can’t fix problems on your site if you don’t know what they are. Using a web crawler tool takes the guesswork out of evaluating your site.

Types of web crawler tools

There are many tools on the market with various features, but they all fall into two categories:

The type of tool you use will depend on your team’s needs and budget. Generally, choosing a cloud-based option will allow for greater collaboration since the program will not need to be stored on an individual’s device.

Once installed, you can configure the crawlers to run at a given interval and generate reports as needed.

Benefits of using web crawler tools

Having your site crawled properly is essential for SEO. In addition to diagnosing site errors, the benefits of using a web crawler tool include:

1. Doesn’t affect site performance

Site crawlers run in the background and will not slow down your site while using it. They will not interfere with your daily tasks and have no effect on anyone browsing your site.

2. Built-in reports

Most crawlers have built-in reporting or analysis functionality and allow you to export these reports to an Excel spreadsheet or other formats. This feature saves you time and allows you to quickly dig deeper into your audit results.

3. Use Automation

A great feature of web crawlers is that you can set a cadence for them to crawl your site. This allows you to regularly track site performance without having to manually generate a crawl report each time.

Performing regular site audits with a crawling tool is a great way to ensure your site is healthy and ranking as it should.

Expand your reach with web crawling

Web crawlers are responsible for finding and indexing online content for search engines. They work by sorting and filtering web pages so that search engines understand what each web page is about. Understanding web crawlers is just one part of effective technical SEO that can dramatically improve your website’s performance.

This article was originally published on July 15, 2021 and has been updated for completeness.

Originally posted Feb 18, 2022 at 7:00:00 AM, updated Feb 18, 2022

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