Canonical selection

Day 1: Crawling 4

Said on stage 2

What Google's documentation says 1

Analysis by the author 1

Day 2: Indexing 47

Shown on screen 12

Said on stage 18

What Google's documentation says 8

Analysis by the author 9

Day 3: Serving: Ranking, Search Console, and Performance 5

Said on stage 3

What Google's documentation says 1

Analysis by the author 1

Across days and sessions 22

1. Stage D2-C393 Day 2 · Handling web duplication

   Google's speaker said that pointing rel=canonical from the pages of a paginated set to the first page can sometimes make sense depending on the goal, for example to make a category page more visible, but that it affects canonicalization and deduplication.

   contradicts
   Docs D1-C115 Day 1 · session not recorded

   Google's crawlers do not click buttons. Each page in a series needs its own URL and an <a href> link to the next page, should not use page 1 as its canonical, and rel=next and rel=prev are no longer used.

2. Stage D2-C429 Day 2 · Lightning session E: Managing Duplicates and Site Moves

   A community speaker said pages carry different link equity, and a canonical leader that is not the strongest page in its group is technically valid but most likely suboptimal for ranking, so the strongest page should be the leader.

   contradicts
   Slide D2-C348 Day 2 · Handling web duplication

   Google forwards the signals attached to every URL in a duplicate cluster, such as links, to the representative URL, so that nothing is lost by showing only one URL.

3. Slide D2-C031 Day 2 · How is HTML interpreted

   Google extracts the rel=canonical link, through which site owners state their preferred canonical URL, and uses it in deduplication and in canonical selection.

   extends
   Docs D1-C128 Day 1 · session not recorded

   Google's canonicalization guide says some duplicate content on a site is normal and not a violation of its spam policies; Google clusters duplicate pages, picks the most representative one as canonical and crawls the duplicates less often.

4. Slide D2-C345 Day 2 · Handling web duplication

   Google's deduplication has three steps: identify and cluster duplicate web pages, pick representative URLs and index the unique pages, and forward signals to the representative URLs.

   extends
   Docs D1-C128 Day 1 · session not recorded

   Google's canonicalization guide says some duplicate content on a site is normal and not a violation of its spam policies; Google clusters duplicate pages, picks the most representative one as canonical and crawls the duplicates less often.

5. Slide D2-C345 Day 2 · Handling web duplication

   Google's deduplication has three steps: identify and cluster duplicate web pages, pick representative URLs and index the unique pages, and forward signals to the representative URLs.

   extends
   Stage D1-C207 Day 1 · How Search works and where's AI?

   Google clusters duplicate pages and selects one page per cluster as its representative, the canonical URL, so that users are not shown duplicates.

6. Stage D2-C346 Day 2 · Handling web duplication

   For deduplication, a cluster is a set of pages Google considers essentially equivalent: Google stores one of them in the index and keeps track of the other related URLs.

   extends
   Stage D1-C207 Day 1 · How Search works and where's AI?

   Google clusters duplicate pages and selects one page per cluster as its representative, the canonical URL, so that users are not shown duplicates.

7. Slide D2-C348 Day 2 · Handling web duplication

   Google forwards the signals attached to every URL in a duplicate cluster, such as links, to the representative URL, so that nothing is lost by showing only one URL.

   extends
   Stage D1-C111 Day 1 · session not recorded

   Gary Illyes said there is no such thing as a duplicate content penalty.

8. Slide D2-C369 Day 2 · Handling web duplication

   Google's slide on structurally similar content asked whether a new URL that fits a known duplicate pattern, such as /buy/seo-service, even needs to be crawled.

   extends
   Docs D1-C128 Day 1 · session not recorded

   Google's canonicalization guide says some duplicate content on a site is normal and not a violation of its spam policies; Google clusters duplicate pages, picks the most representative one as canonical and crawls the duplicates less often.

9. Stage D2-C379 Day 2 · Handling web duplication

   rel=canonical is probably the most common way site owners signal duplicates, but it is very often wrong, for example a tag whose value reads 'canonical target' instead of a real URL (the example is partly unclear in the recording), so Google can only sometimes trust it.

   extends
   Slide D2-C031 Day 2 · How is HTML interpreted

   Google extracts the rel=canonical link, through which site owners state their preferred canonical URL, and uses it in deduplication and in canonical selection.

10. Stage D2-C380 Day 2 · Handling web duplication

    Many SEOs assume Google must follow their rel=canonical, but because people sometimes get it wrong, Google has to make its own judgment about the canonical.

    extends
    Analysis D1-C113 Day 1 · session not recorded

    The real cost of duplicates is control and crawling: Google may choose a canonical you did not want, and every copy is still crawled. Copied or scraped content is a separate spam-policy issue.

11. Docs D2-C395 Day 2 · Handling web duplication

    Google's 2013 post on rel=canonical mistakes says pointing rel=canonical from page 2 or later of a paginated series to page 1 is incorrect because the pages are not duplicates, and that it would result in the content on later pages not being indexed at all.

    extends
    Docs D1-C115 Day 1 · session not recorded

    Google's crawlers do not click buttons. Each page in a series needs its own URL and an <a href> link to the next page, should not use page 1 as its canonical, and rel=next and rel=prev are no longer used.

12. Stage D2-C401 Day 2 · Lightning session E: Managing Duplicates and Site Moves

    Broken canonical tags can make the wrong pages of a site show up in search results.

    extends
    Analysis D1-C113 Day 1 · session not recorded

    The real cost of duplicates is control and crawling: Google may choose a canonical you did not want, and every copy is still crawled. Copied or scraped content is a separate spam-policy issue.

13. Stage D2-C408 Day 2 · Lightning session E: Managing Duplicates and Site Moves

    A community speaker advised auditing canonicals as whole canonical groups rather than pair by pair, paying special attention to each group's canonical leader.

    extends
    Docs D1-C128 Day 1 · session not recorded

    Google's canonicalization guide says some duplicate content on a site is normal and not a violation of its spam policies; Google clusters duplicate pages, picks the most representative one as canonical and crawls the duplicates less often.

14. Stage D2-C408 Day 2 · Lightning session E: Managing Duplicates and Site Moves

    A community speaker advised auditing canonicals as whole canonical groups rather than pair by pair, paying special attention to each group's canonical leader.

    extends
    Stage D2-C398 Day 2 · Handling web duplication

    Google's speaker suggested checking rel=canonical links with a crawler such as Screaming Frog to make sure they are reasonable.

15. Stage D2-C701 Day 2 · Deciding what goes in the index?

    When Google already has duplicate information for a document, for example when reprocessing it, index selection uses it to drop non-canonical duplicates from further processing, so that, as the speaker put it, only canonicals end up in search results (a simplification; see D2-C703).

    extends
    Docs D1-C128 Day 1 · session not recorded

    Google's canonicalization guide says some duplicate content on a site is normal and not a violation of its spam policies; Google clusters duplicate pages, picks the most representative one as canonical and crawls the duplicates less often.

16. Stage D2-C701 Day 2 · Deciding what goes in the index?

    When Google already has duplicate information for a document, for example when reprocessing it, index selection uses it to drop non-canonical duplicates from further processing, so that, as the speaker put it, only canonicals end up in search results (a simplification; see D2-C703).

    extends
    Slide D2-C345 Day 2 · Handling web duplication

    Google's deduplication has three steps: identify and cluster duplicate web pages, pick representative URLs and index the unique pages, and forward signals to the representative URLs.

17. Stage D2-C873 Day 2 · Lightning session E: Managing Duplicates and Site Moves

    A community speaker said that, under the canonical link specification, an improperly declared canonical tag can also be ignored completely by the application that processes it, not only replaced by that application's own heuristic.

    extends
    Stage D2-C402 Day 2 · Lightning session E: Managing Duplicates and Site Moves

    According to the canonical link specification cited by a community speaker, when a canonical tag is declared improperly, the application that processes it may apply its own heuristic and decide what to do instead.

18. Stage D2-C882 Day 2 · Lightning session E: Managing Duplicates and Site Moves

    In a community case study, an old URL got a 301 redirect only when a new page served the same intent; URLs with no same-intent match were removed with an error status instead of being redirected (the exact code is unclear in the recording).

    extends
    Slide D2-C396 Day 2 · Handling web duplication

    Google's closing suggestions on duplication: use redirects for site migrations, use HTTP result codes, don't block agents, check your rel=canonical links, use hreflang links to help Google localize, report weird canonicals in the forums, make secure pages that work, and keep canonical signals clear.

19. Stage D3-C642 Day 3 · How long does it take to..?

    Google treats a site move as a complex canonicalization process in which every signal of the old site is recalculated and moved to the new one, and every indexing process has to run.

    extends
    Stage D2-C351 Day 2 · Handling web duplication

    Google treats a site migration as deduplication across sites, in which the site owner says the old and the new domain are the same and that Google should pick the new domain, so deduplication also helps Google handle migrations.

20. Stage D1-C207 Day 1 · How Search works and where's AI?

    Google clusters duplicate pages and selects one page per cluster as its representative, the canonical URL, so that users are not shown duplicates.

    repeats
    Docs D1-C128 Day 1 · session not recorded

    Google's canonicalization guide says some duplicate content on a site is normal and not a violation of its spam policies; Google clusters duplicate pages, picks the most representative one as canonical and crawls the duplicates less often.

21. Stage D1-C445 Day 1 · Q&A

    One fix for parameter variants of a URL is to work out the normalised URL and redirect the variants to it: the redirects cost crawl budget at first, but leave the site with a clean slate.

    repeats
    Stage D1-C403 Day 1 · Lightning session C: Crawling

    A community speaker advised that a web application compute the expected URL for every request, for example with reverse routing from the page type and ID, and redirect or return an error page when the requested URL differs.

22. Stage D2-C402 Day 2 · Lightning session E: Managing Duplicates and Site Moves

    According to the canonical link specification cited by a community speaker, when a canonical tag is declared improperly, the application that processes it may apply its own heuristic and decide what to do instead.

    repeats
    Stage D2-C380 Day 2 · Handling web duplication

    Many SEOs assume Google must follow their rel=canonical, but because people sometimes get it wrong, Google has to make its own judgment about the canonical.

Built on these claims 14

Developer requirements 14

• MustDocumentedDEV-CAN-03

  Put exactly one absolute rel=canonical in the server-rendered head of every indexable page

  Rests on 8 claims, 7 of them in this topic

• MustDocumentedDEV-CAN-05

  Make all canonical signals agree: redirects, rel=canonical, internal links, sitemaps and hreflang

  Rests on 6 claims, 5 of them in this topic

• ShouldDocumentedDEV-CAN-08

  Make pages that share a URL pattern differ in their main content

  Rests on 6 claims, 5 of them in this topic

• MustDocumentedDEV-CAN-01

  Use permanent server-side redirects (301 or 308) for moved URLs, straight to the final URL

  Rests on 10 claims, 3 of them in this topic

• MustDocumentedDEV-CAN-02

  Serve one host over HTTPS with a valid certificate and redirect every other origin to it

  Rests on 4 claims, 3 of them in this topic

• ShouldDocumentedDEV-MON-06

  Audit canonical groups with a crawler on a schedule

  Rests on 5 claims, 3 of them in this topic

• MustDocumentedDEV-URL-06

  Give each page of a paginated series its own URL, its own canonical and an <a href> to the next page

  Rests on 6 claims, 3 of them in this topic

• ShouldDocumentedDEV-URL-09

  If facet URLs must be crawlable, use & separators, a fixed filter order and 404 for empty results

  Rests on 5 claims, 3 of them in this topic

• AvoidDocumentedDEV-CAN-07

  Never leave staging, preview or mirror copies of the site publicly crawlable

  Rests on 2 claims, 2 of them in this topic

• ShouldDocumentedDEV-MON-10

  Plan releases and fixes around Google's processing times, and judge results only after them

  Rests on 11 claims, 2 of them in this topic

• ShouldDocumentedDEV-URL-05

  Publish XML sitemaps listing only canonical, indexable URLs with accurate lastmod

  Rests on 11 claims, 2 of them in this topic

• MustDocumentedDEV-CAN-04

  Point every canonical directly at a final URL that returns 200, is indexable and is linked

  Rests on 8 claims, 1 of them in this topic

• ShouldDocumentedDEV-INT-08

  Differentiate same-language country versions beyond boilerplate and mark them with region codes

  Rests on 6 claims, 1 of them in this topic

• ShouldDocumentedDEV-URL-11

  Compute the expected URL for every request and redirect variants to it

  Rests on 8 claims, 1 of them in this topic

Sources 15

• In-depth guide to how Google Search works Google Search Central · checked 3 October 2026
• What is canonicalization Google Search Central · checked 3 October 2026
• How to specify a canonical URL with rel="canonical" and other methods Google Search Central · checked 3 October 2026
• URL Inspection tool Google Search Console Help · checked 4 October 2026
• Redirects and Google Search Google Search Central · checked 4 October 2026
• Fix canonicalization issues Google Search Central · checked 3 October 2026
• Troubleshoot Google Search crawling errors Google Search Central · checked 2 October 2026
• 5 common mistakes with rel=canonical Search Central blog (8 April 2013) · checked 3 October 2026
• Pagination, incremental page loading, and their impact on Google Search Google Search Central · checked 3 October 2026
• How to move a site Google Search Central · checked 4 October 2026
• Tell Google about localized versions of your page Google Search Central · checked 3 October 2026
• Specify your canonical Search Central blog (12 February 2009) · checked 2 October 2026
• Page indexing report Google Search Console Help · checked 4 October 2026
• Latest documentation updates Google Search Central · checked 3 October 2026
• Optimize your crawl budget Google · checked 4 October 2026