Search Central LiveDeep Dive Europe 2026

Knowledge base v2.13.0 · Community edition · data through 2 October 2026

Topic · Serving and ranking

Ranking systems and signals

Google stressed that there is not one single ranking system: its slide listed spam detection, reviews, BERT, MUM, RankBrain, freshness, deduplication, crisis information and other systems, and pointed site owners to Google's published ranking systems guide, which says MUM is not currently used for general ranking. Quality is one of the most important of hundreds of ranking signals, so maximising a single signal does not work, and the systems change over time. The quality talk said PageRank is not used so much anymore, while Google's guide says it has evolved and is still part of the core ranking systems. Google said the same quality signal is also used to order candidates at retrieval (said at the event). Day 1's slides had placed BERT in indexing and RankBrain in serving, and Google's guide already said then that MUM is used only for specific applications. Author’s view: read the slide as a list of systems Google runs, not as proof that each one ranks every query, and read the PageRank remark as links weighing less among many signals, not as PageRank being switched off. Day 1's second recording added that signals calculated during indexing are stored and used both for index selection and later for ranking, that quality is one of the most important things in ranking, and that a higher crawl rate does not make a URL rank better; on Day 2 Gary Illyes said the main content is what Google considers when ranking a page.

Based on D3-C133, D3-C135, D3-C140, D3-C131, D3-C143, D3-C141, D3-C136, D3-C138, D3-C137, D3-C083, D3-C084, D1-C042, D1-C043, D1-C130, D1-C205, D1-C216, D1-C391, D2-C868

23 claims · raised in 5 sessions · said or shown on Day 1 and Day 2 and Day 3

Open in Reef mapOpen in Graph

Things in this topic 3

Counts are claims that name the thing. All things

What to do

  • Plan improvements across content quality, internal links, page experience and freshness together instead of pushing one metric.

Day 1: Crawling 4

Said on stage 4

StageConsistent with docsD1-C205

Signals calculated for a page during indexing are stored in the index and used both to decide whether the page gets indexed and, later, for ranking.

Speaker Cherry PrommawinIn Day 1, 11:45 · How Search works and where's AI?Evidence transcript

  • Extends D1-C037 Day 1: For classic Search, crawling means Googlebot, scheduling and robots.txt, with AI used in parts such as…
  • Extended by D2-C687 Day 2: Index selection uses the signals calculated earlier in indexing for each document it has to select or discard.
StageD1-C390

An audience member asked, in a question submitted before the event, whether crawl frequency affects the ranking position of a URL.

From the audienceIn Day 1, 16:00 · How Google thinks about crawl budgetEvidence transcript

  • Answered by D1-C391 Day 1: A higher crawl rate does not make a URL rank better; it only means Google checks the site more often.
  • Answered by D1-C392 Day 1: Frequent crawling is usually a consequence, not a cause: Google visiting a site more often tends to signal…
StageConfirmed by docsD1-C391

A higher crawl rate does not make a URL rank better; it only means Google checks the site more often.

“if your crawl rate is increased, that doesn't mean that you would rank better.”

Speaker Cherry PrommawinIn Day 1, 16:00 · How Google thinks about crawl budgetEvidence transcript

  • Answers D1-C390 Day 1: An audience member asked, in a question submitted before the event, whether crawl frequency affects the…

Day 2: Indexing 1

Said on stage 1

StageConsistent with docsD2-C868

Gary Illyes said the main content is what Google considers when ranking a page.

“It's the main content that we consider for ranking.”

Speaker Gary IllyesIn Day 2, 11:30 · Understanding what's on a pageEvidence transcript

Things

Used byrequirement DEV-HTM-01

  • Extends D2-C028 Day 2: Google extracts every element of a page so that it can tell the header, the navigation and the main content…

Day 3: Serving: Ranking, Search Console, and Performance 18

Shown on screen 1

SlideConfirmed by docsD3-C133

Google's slide said there is not one single ranking system and named spam detection systems, the reviews system, BERT, MUM, RankBrain, freshness systems, deduplication systems, crisis information systems and link analysis systems (PageRank).

“There’s not one single ranking system...”

Wording checked against the slide or recording

Speaker GoogleIn Day 3, 11:15 · How Google thinks about QualityEvidence slide photo, transcript

Things

Said on stage 11

StageNot in docsD3-C083

Google called quality the most important of the signals used to order candidates at retrieval: a URL of high quality is more likely to be retrieved from the index for specific queries.

“if the quality of a URL is high, then it's more likely to be retrieved from the index for specific queries.”

Speaker Gary IllyesIn Day 3, 10:25 · Making sense of users' queriesEvidence transcript

Used byglossary term Retrieval

  • Extends D2-C722 Day 2: Each document in Google's index has pretty much all the signals calculated for it attached, for example…
StageConsistent with docsD3-C084

The same quality signal that Google uses at retrieval is also used in ranking when results are served.

Speaker Gary IllyesIn Day 3, 10:25 · Making sense of users' queriesEvidence transcript

  • Extended by D3-C131 Day 3: Google's quality talk said quality is one of the most important ranking signals, although Google uses…
StageConsistent with docsD3-C131

Google's quality talk said quality is one of the most important ranking signals, although Google uses hundreds of ranking signals (the word 'quality' is a repaired speech-to-text reading).

Speaker GoogleIn Day 3, 11:15 · How Google thinks about QualityEvidence transcript

  • Extends D3-C084 Day 3: The same quality signal that Google uses at retrieval is also used in ranking when results are served.
StageConsistent with docsD3-C143

Google's quality talk warned that trying to maximise one ranking signal does not work, because Google uses hundreds of ranking signals.

“Big takeaway: always remember, there's hundreds of ranking signals.”

Speaker GoogleIn Day 3, 11:15 · How Google thinks about QualityEvidence transcript

What Google's documentation says 1

Analysis by the author 5

AnalysisD3-C096

The retrieval talk went further than Google's documentation, which says Search returns the highest-quality and most relevant results and lists quality among key ranking signals, but never describes quality as deciding which pages are retrieved from the index at all.

Author Ibrahim AnjroAnnotates Day 3, 10:25 · Making sense of users' queries

AnalysisD3-C135

The quality talk's slide listed MUM among Google's ranking systems, while Google's ranking systems guide says MUM is not currently used for general ranking in Search; read the slide as a list of systems Google runs, not as proof that each one ranks every query.

Author Ibrahim AnjroAnnotates Day 3, 11:15 · How Google thinks about Quality

  • Extends D1-C130 Day 1: Google's ranking systems guide says MUM is not currently used for general ranking in Search, only for…
AnalysisD3-C137

The remark that PageRank is not used so much anymore differs from Google's ranking systems guide, which says PageRank has evolved a lot and continues to be part of the core ranking systems; read it as PageRank weighing less among many signals, not as PageRank being switched off, so links still matter.

Author Ibrahim AnjroAnnotates Day 3, 11:15 · How Google thinks about Quality

Things

Across days and sessions 6

  1. Stage D1-C205 Day 1 · How Search works and where's AI?

    Signals calculated for a page during indexing are stored in the index and used both to decide whether the page gets indexed and, later, for ranking.

    extends
    Slide D1-C037 Day 1 · How Search works and where's AI?

    For classic Search, crawling means Googlebot, scheduling and robots.txt, with AI used in parts such as scheduling. Indexing is one big but not limitless index that calculates signals and understands more than words, with AI such as BERT. Serving uses hundreds of signals tailored to the moment, with AI such as RankBrain.

  2. Stage D2-C687 Day 2 · Deciding what goes in the index?

    Index selection uses the signals calculated earlier in indexing for each document it has to select or discard.

    extends
    Stage D1-C205 Day 1 · How Search works and where's AI?

    Signals calculated for a page during indexing are stored in the index and used both to decide whether the page gets indexed and, later, for ranking.

  3. Stage D2-C868 Day 2 · Understanding what's on a page

    Gary Illyes said the main content is what Google considers when ranking a page.

    extends
    Slide D2-C028 Day 2 · How is HTML interpreted

    Google extracts every element of a page so that it can tell the header, the navigation and the main content apart, and a slide labelled the main content as very important.

  4. Stage D3-C083 Day 3 · Making sense of users' queries

    Google called quality the most important of the signals used to order candidates at retrieval: a URL of high quality is more likely to be retrieved from the index for specific queries.

    extends
    Stage D2-C722 Day 2 · How does the index look like?

    Each document in Google's index has pretty much all the signals calculated for it attached, for example quality signals plus the page's country and language, according to an illustration the speaker called an approximation of the real structure.

  5. Stage D3-C131 Day 3 · How Google thinks about Quality

    Google's quality talk said quality is one of the most important ranking signals, although Google uses hundreds of ranking signals (the word 'quality' is a repaired speech-to-text reading).

    extends
    Stage D3-C084 Day 3 · Making sense of users' queries

    The same quality signal that Google uses at retrieval is also used in ranking when results are served.

  6. Analysis D3-C135 Day 3 · How Google thinks about Quality

    The quality talk's slide listed MUM among Google's ranking systems, while Google's ranking systems guide says MUM is not currently used for general ranking in Search; read the slide as a list of systems Google runs, not as proof that each one ranks every query.

    extends
    Docs D1-C130 Day 1 · How Search works and where's AI?

    Google's ranking systems guide says MUM is not currently used for general ranking in Search, only for specific applications such as COVID-19 vaccine searches and featured snippet callouts.

Built on these claims 1

Developer requirements 1

Sources 7