A Comprehensive Guide to SEO, AEO, and GEO Definitions - Google's Official 2025 Standards

In July 2025, Google Search Central Live Deep Dive APAC featured Gary Illyes revealing how Google Search works in the AI era. As Google's Webmaster Trends Analyst, he is a key spokesperson who directly explains complex technical topics like crawling and indexing to the SEO community.

In this article, we will clearly organize the SEO, AEO, and GEO terminology based on his presentation materials containing Google's official position. In particular, we will examine in detail how the existing definitions widely used in the industry differ from Google's official announcement.

Previous Expert Definitions of SEO, AEO, and GEO

With the emergence of AI Overview and AI search services, the SEO industry has defined various terms to explain new optimization methodologies for the AI era. Our Answer Global team has also been deeply involved, being among the first domestically to establish Generative Engine Optimization (GEO) consulting processes and launching the AI search visibility service SCOPE. Let's first look at the concepts of SEO, AEO, and GEO as previously defined by SEO experts.

SEO (Search Engine Optimization)

SEO (Search Engine Optimization) refers to all activities that understand search user intent, create high-quality content matching that intent, and optimize website structure to increase traffic through organic search result rankings.

Google search results for 'Generative Engine Optimization Consulting' keyword - Traditional SEO-style link listing search results

AEO (Answer Engine Optimization)

AEO (Answer Engine Optimization) refers to a strategy focused on instantly resolving user queries by optimizing content to appear as direct 'answers' on the Search Engine Results Page (SERP) for user questions.

Google search results for 'Generative Engine Optimization Consulting' keyword - AEO-optimized answer-type search results (Featured Snippets, People Also Ask, etc.)

To understand AEO more accurately, we need to examine its evolution.

The Evolution of AEO

Beginning: Featured Snippets

Google moved beyond simply listing website links to extract the most suitable answer for user questions from specific webpages and display it at the top of search results (Position Zero). SEO experts studied optimization methods to get their content displayed in this 'answer box,' and this became the starting point of AEO.

Expansion: Various Answer Formats

Subsequently, Google began providing direct answers in various formats, including 'People Also Ask,' 'Rich Snippets' showing ratings or recipe information, and 'Knowledge Panels' summarizing information about people or places. The scope of AEO naturally expanded to optimization for all these 'answer' areas.

Present: AI Overview

AI Overview represents the most advanced form of this evolution. While previously answers were 'extracted' from a single webpage, now AI synthesizes and summarizes information from multiple webpages to 'generate' answers.

GEO (Generative Engine Optimization)

GEO (Generative Engine Optimization) refers to the optimization process of ensuring that when generative AI creates answers to user questions, it learns and cites your content as a trustworthy information source, favorably reflecting it in the final answer.

Google Gemini's response to 'Tell me companies that provide GEO consulting' - GEO-optimized generative AI response results

As such, experts have distinguished and defined three optimization concepts—SEO, AEO, and GEO—under the hypothesis that their methodologies would differ. While debates continued, including counterarguments that "only SEO exists, and AEO and GEO don't exist," Google's official announcement on July 28, 2025, resolved everything.

Google's Official Announcement: "AEO Does Not Exist"

According to Google Search Analyst Gary Illyes, AEO does not exist. He explained: "Both AI Overview and AI Mode operate based on completely the same system as traditional search for all processes of collecting (Crawling), storing (Indexing), and serving information."

Crawling: The process where Googlebot visits webpages on the internet and reads their content

Indexing: The process of systematically organizing and storing collected information in Google's massive database

Serving: The process of finding and displaying the most appropriate results from stored information when users search

In other words, from Google's perspective, there is no separate optimization methodology called AEO for appearing in Google Search AI Overview or AI Mode responses, meaning SEO = AEO. This is because both AI Overview and AI Mode, including answer-format search results, are ultimately provided through the same crawling, indexing, and ranking systems.

Same Crawler

The existing 'Googlebot' that collects webpages handles information collection for AI Overview/AI Mode. There is no separate 'AI Mode crawler.'

Same Index

AI Overview responses are generated based on the massive web 'index' organized by Googlebot. Content from pages not indexed by Google cannot appear in AI Overview/AI Mode.

Same SEO Principles

They emphasized multiple times that special SEO (AEO) for AI Overview/AI Mode is unnecessary. Existing practices like creating high-quality content and technical SEO optimization—'standard SEO'—apply as is.

*Google AI Mode is a service not yet available in Korea. It can be understood as using AI in Google Search. For detailed explanation, please refer to Google's document Expanding AI Overviews and introducing AI Mode.

What About GEO Then?

Following this official announcement at Google Search Central Live Deep Dive APAC, views like "There's no such thing as AEO or GEO, only SEO" are being shared on LinkedIn and in SEO/marketing communities. However, this is not accurate. Google's official presentation materials also indicated that Gemini operates through different processes.

Let me explain based on materials released at the conference. The content below pertains to 'Gemini' shown in blue at the bottom of the image—its Crawling, Indexing, and Serving processes.

Google's slide explaining how AI mode, AI overview, and Gemini work

Source: Dan Taylor, Search Engine Journal

Crawling

Instead of specifying 'Googlebot,' the plural 'crawlers' was used. This means that separate crawlers are used together for Gemini model training or page collection.

Indexing

The expression "Uses some of the same technologies, e.g., tokenization, deduping" means that some of the same technologies like tokenization and deduplication are used. In other words, Gemini uses additional technologies beyond those implemented in existing Google Search during the indexing process.

Serving

The expression "Grounds on Search Index" was used. This means that since Gemini is not part of the search system, it accesses Google's search index as an 'external tool' when needed to retrieve recent information and enhance its responses.

In summary, while Gemini operates based on existing Google Search systems across all crawling, indexing, and serving processes, it does not use the existing Google Search system exactly as is. Accordingly, Generative Engine Optimization (GEO)—work for AI search optimization—remains a subject of research.

2025 SEO, AEO, GEO Terminology Summary Conclusion

Here is a summary of the key points explained so far:

Category	SEO	AEO	GEO
Definition	Search Engine Optimization	Answer Engine Optimization	Generative Engine Optimization
Target System	Google Search	AI Overview, AI Mode	Gemini
Google's Official Position	Standard Optimization	Does Not Exist (Same as SEO)	Separate Processes Exist
Crawling	Googlebot	Googlebot (Same)	Separate Crawlers
Indexing	Google Search Index	Google Search Index (Same)	Some Tech Shared + Additional Tech
Serving	Provides Search Results	Provides Search Results (Same)	External Tool Access to Search Index
Optimization Necessity	Essential	Unnecessary (SEO Sufficient)	Requires Separate Strategy

We hope this article helped you understand the relationship and concepts of SEO, AEO, and GEO. If you're curious about how Gemini's AI search works following this article, we recommend reading the article below as well.