Crawlability and indexability are two critical aspects of technical SEO. They determine whether search engines can discover, read, and understand your website's content. If search engines cannot crawl or index your pages effectively, they cannot rank them, which means your site will not appear in search engine results. Let's break these concepts down in more detail.
1. Crawlability
Crawlability refers to a search engine's ability to access and explore the pages on your website. Search engines use automated bots (like Google's Googlebot) to crawl web pages. These bots follow links, read the content, and index the pages based on what they find.
Factors that Affect Crawlability:
Robots.txt File: The robots.txt file is a file placed in the root directory of your website that tells search engine bots which pages or sections of your site they should crawl or ignore. If your robots.txt is configured incorrectly, it can block search engines from crawling important pages, potentially harming your SEO.
Example of a robots.txt that blocks all crawlers from your site:
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User-agent: *
Disallow: /
Ensure Important Pages Are Not Blocked: You need to make sure that your key pages, such as product pages, blog posts, or category pages, are not blocked by robots.txt.
Internal Linking: Search engine bots use links to navigate through your site. If a page is not linked to from other pages (either directly or via navigation), it might be considered "orphaned" and may not be discovered by search engines.
Internal Linking Strategy: Ensure you have a solid internal linking structure where important pages are linked from other parts of your site.
Sitemaps: An XML sitemap is a file that lists all the pages you want search engines to crawl and index. It acts as a roadmap for search engines, helping them discover all of your important content.
Google Search Console: Submitting your XML sitemap to Google Search Console ensures Googlebot knows which pages to crawl. This is especially useful for larger sites with many pages.
Crawl Budget: Crawl budget refers to the number of pages Googlebot crawls on your site within a given time. A higher crawl budget is important for larger sites, as it ensures Google can crawl your most important pages regularly.
Optimizing Crawl Budget: To optimize your crawl budget:
Minimize the number of low-value or duplicate pages.
Use internal linking to prioritize key pages.
Make sure Googlebot can crawl pages quickly and efficiently (reduce server response time and eliminate any unnecessary redirects).
Crawl Errors: Crawl errors occur when a search engine bot is unable to reach a page. These could be caused by broken links, server issues, or other technical problems. Identifying and fixing crawl errors is crucial.
Google Search Console: Use Google Search Console to check for crawl errors (404 errors, DNS issues, etc.) and fix them.
How to Ensure Good Crawlability:
Check Your Robots.txt File: Ensure that no important pages are being blocked by your robots.txt file.
Use an XML Sitemap: Create and submit an XML sitemap to search engines.
Fix Broken Links: Regularly check for broken links and 404 errors.
Improve Site Structure: Use clear, hierarchical internal linking and ensure all important pages are accessible.
Monitor Crawl Budget: For larger sites, ensure efficient use of your crawl budget by prioritizing key pages and removing duplicate content.
2. Indexability
Indexability refers to a search engine's ability to add pages from your website into its index after crawling them. Once a page is crawled, the search engine decides whether or not to include it in its search index. If a page is not indexed, it won't appear in search results.
Factors that Affect Indexability:
Meta Robots Tags: The meta robots tag is a tag placed in the <head> section of a page's HTML code that tells search engines whether to index the page or not. For example:
noindex: Tells search engines not to index the page.
index: Tells search engines to index the page (this is the default).
Example of a noindex meta tag:
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<meta name="robots" content="noindex, nofollow">
Noindexing Unnecessary Pages: It's common practice to noindex pages like login pages, search result pages, or duplicate content pages to avoid unnecessary indexing and to focus crawl budget on valuable pages.
Canonical Tags: Canonical tags are used to indicate the preferred version of a page when multiple versions of the same content exist (e.g., similar product pages or content accessible via different URLs). This helps prevent duplicate content issues and ensures that the primary version is indexed.
Example of a canonical tag:
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<link rel="canonical" href="https://www.example.com/primary-page/">
Avoid Duplicate Content: Make sure to use canonical tags correctly to point to the "preferred" version of a page to avoid penalties related to duplicate content.
Blocked Content via Meta Tags: Pages can be blocked from indexing by using the noindex directive, which tells search engines not to add the page to the index. This can be useful for pages you want to exclude from search results.
Be cautious with noindex tags, as they can prevent important pages from appearing in search results.
Crawl Delay: Some websites set a crawl delay in their robots.txt file to manage the frequency of crawls. If the crawl delay is set incorrectly, it might limit the search engines' ability to crawl and index your pages effectively.
Duplicate Content: Duplicate content can hurt your website’s indexability. If a search engine finds the same content at multiple URLs, it might choose to index one version and ignore others, or worse, penalize the site for duplicate content.
Canonical Tags: Use canonical tags to indicate the correct version of the content.
301 Redirects: For duplicate pages or content, implement permanent 301 redirects to the preferred page.
NoFollow Links: Links with a rel="nofollow" attribute do not pass link equity (ranking power) to the destination page. While this does not prevent crawling, it may impact the indexability of linked pages if search engines do not consider them important.
Example of NoFollow link:
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<a href="https://www.example.com" rel="nofollow">Link Text</a>
How to Ensure Good Indexability:
Use Meta Robots Tags Correctly: Ensure that critical pages are not accidentally set to noindex.
Canonical Tags: Use canonical tags to resolve duplicate content issues and specify the preferred version of pages.
Regularly Check Google Search Console: Use Google Search Console to monitor which pages are indexed and identify any indexing issues (e.g., pages with noindex tags, blocked resources).
Avoid Duplicate Content: Use unique content and proper canonicalization to prevent duplicate content problems.
Monitor Server Response: Ensure that your server returns the correct HTTP status codes (e.g., 200 for valid pages, 301 for redirects, 404 for non-existent pages) to help search engines properly index your content.
Tools for Analyzing Crawlability & Indexability:
Google Search Console:
Coverage Report: Identifies which pages have been indexed and if there are any crawl errors.
URL Inspection Tool: Allows you to inspect a URL to see whether it’s crawled, indexed, and if there are any issues.
Sitemaps: You can submit sitemaps and track whether Google is successfully crawling all of your pages.
Screaming Frog SEO Spider:
A desktop tool that crawls your site and provides detailed reports on technical SEO aspects like broken links, duplicate content, meta tags, and robots.txt configuration.
Ahrefs / SEMrush:
Both of these tools offer site audits that can help identify crawling issues, broken links, and other technical SEO problems that affect crawlability and indexability.
Conclusion
Ensuring good crawlability and indexability is vital to SEO success. If search engines cannot crawl and index your pages, your content won't appear in search results, which means no organic traffic. By optimizing the structure of your site, using sitemaps, managing robots.txt, fixing errors, and handling duplicate content, you can ensure that your site is both crawlable and indexable, boosting your chances of ranking higher in search engines.
If you have specific questions about crawlability or indexability, feel free to ask!