Algorithms

Algorithm volatility

SERP volatility · Ranking flux

Day-to-day fluctuation in rankings caused by continuous algorithm changes, index updates and testing, distinct from confirmed named updates.

BERT

Bidirectional Encoder Representations from Transformers

A transformer language model Google applied to search from 2019, improving understanding of word order, prepositions and context within queries and passages.

Core update

Broad core algorithm update

A significant, broad change to Google's ranking systems, announced in advance and rolled out over one to several weeks, typically a few times a year.

Deduplication system

Duplicate filtering

Google's system for ensuring results are not dominated by near-identical pages, filtering duplicates so users see a varied set of sources.

Exact-match domain system

EMD

Google's system preventing low-quality sites from ranking merely because their domain name matches a query, introduced as an update in 2012.

Expired domain abuse

Domain resurrection

Buying an expired domain and repurposing it to host unrelated low-value content in order to inherit its accumulated ranking signals.

Freshness systems (QDF)

Query Deserves Freshness

Google's systems that boost recent content for queries where recency matters, such as breaking news, sports scores or evolving topics.

Google Content Warehouse API leak

Google API leak · 2024 documentation leak

The May 2024 publication of thousands of internal Google Search API documentation attributes, which named ranking-related features not previously disclosed.

Google ranking systems

Ranking systems guide

Google's documented list of the systems that generate rankings, distinguished from one-off 'updates' to those systems, and including retired ones.

Google spam policies

Webmaster spam policies

Google's documented list of behaviours that can cause lower rankings or removal, covering cloaking, doorways, hacked content, keyword stuffing, link spam, scraped content…

Helpful content system and updates

HCU

A Google system launched in August 2022 to demote sites with a high proportion of content made for search engines, integrated into core ranking with the March 2024 core…

Hummingbird

Google's 2013 rewrite of its core ranking infrastructure, shifting emphasis from individual keywords toward the meaning of whole queries.

Local search updates (Pigeon, Possum, Vicinity)

Pigeon · Possum · Vicinity update

Informally named updates that shaped local ranking: Pigeon (2014) tied local results to web signals, Possum (2016) changed filtering, Vicinity (2021) raised proximity's…

Manual action

Manual penalty

A demotion or removal applied by a human reviewer at Google for a spam policy violation, reported in Search Console with a reconsideration process.

Medic update

August 2018 core update

The industry nickname for Google's August 2018 broad core update, which had pronounced effects on health, medical and other YMYL sites.

MUM

Multitask Unified Model

Google's multimodal, multilingual model announced in 2021, able to transfer knowledge across languages and formats to answer complex comparative questions.

Navboost

A Google ranking component, described in United States antitrust testimony, that uses aggregated historical click and query data to adjust rankings.

Neural matching

A Google system that uses neural networks to understand how queries relate to page concepts, bridging vocabulary gaps between what users type and how pages are written.

Original content system

Original reporting

Google's system for surfacing original reporting and source content more prominently than the derivative coverage that follows it.

Panda

Farmer update

Google's 2011 quality algorithm targeting thin, duplicated and low-value content, later folded into the core ranking algorithm and now retired as a named system.

Parasite SEO

Rented authority

The practitioner term for ranking content on someone else's high-authority domain instead of your own, now largely covered by Google's site reputation abuse policy.

Penguin

Webspam update

Google's link spam algorithm launched in 2012; since version 4.0 in 2016 it runs in real time within the core algorithm and devalues spam links rather than penalising sites.

RankBrain

Google's first machine-learning ranking system, introduced in 2015, which helps interpret how queries relate to concepts, especially unfamiliar ones.

Reviews system

Product reviews update

Google's system for rewarding in-depth review content that demonstrates first-hand expertise, broadened in 2023 from products to services, businesses and media.

Scaled content abuse

Mass-produced content

Generating many pages primarily to manipulate rankings rather than help users, whether by AI, templates, scraping, or stitching content together.

Scraped content

Copied content

Republishing content taken from other sites with no original value added; a spam policy violation and a common source of duplicate-content confusion.

Security issues and hacked content

Hacked spam

Malware, phishing, deceptive pages or injected spam on a site, reported in Search Console and often accompanied by browser warnings.

Site reputation abuse

Parasite SEO

Publishing third-party content on a host site to exploit that site's ranking signals; a Google spam policy violation regardless of first-party oversight.

Spam updates

Spam update

Announced improvements to Google's automated spam detection, distinct from core updates, targeting violations of the spam policies.

SpamBrain

Google's AI-based spam prevention system, used to detect spam at crawl and ranking time and to identify and neutralise unnatural links.

Topic authority system

A Google system, described for news surfaces, that surfaces publications with demonstrated expertise in a subject or place more prominently for related queries.

Twiddlers

Google's internal term, surfaced in antitrust testimony and leaked documentation, for re-ranking functions applied on top of a core retrieval score.