How do search engines work? Google, Bing and Co.
Search engines are software systems that systematically crawl the internet (crawling), store the found content in a database (indexing), and display the most relevant results in an ordered list when a search query is made (ranking).
Key Takeaways
- ✓Search engines work in three steps: Crawling (Googlebot retrieves pages and follows links), Indexing (storage in a database), and Ranking (sorting per query).
- ✓A SERP is a composite layout of organic results, ads (SEA), Featured Snippets, Knowledge Panel, and more recently AI Overviews.
- ✓Ranking is based on over 200 signals that condense into four levers: relevance, backlinks, technical SEO, and user experience.
- ✓E-E-A-T (since December 2022 with an additional E for Experience) is a quality framework that matters especially for YMYL and B2B topics.
- ✓In Austria, Google dominates with 81.87 percent market share; DuckDuckGo and Ecosia largely rely on the Bing index, which is why Bing visibility remains important.
- ✓AI search systems like ChatGPT, AI Overviews, Perplexity, and Claude add a synthesis layer to the process; Generative Engine Optimization (GEO) aims at citability in these answers.
- ✓Black-hat tactics violate Google's spam policies and risk penalties; white-hat SEO with substance and clean technical implementation is the sustainable path in B2B.
To understand SEO, you must first understand how search engines work. The process can be divided into three phases: Crawling, Indexing, and Ranking.
Phase 1: Crawling
Search engines deploy automated programs called crawlers or spiders. Google's crawler is called Googlebot. It visits web pages, reads their content, and follows links on the page to discover additional pages. This process runs continuously and captures billions of pages daily.
The robots.txt file controls which areas of a website may be crawled. The XML Sitemap provides search engines with a structured overview of all important pages. Both files are fundamental tools of technical SEO.
Phase 2: Indexing
After Crawling, Google analyzes the page content: text, images, videos, and structured data. The extracted information is stored in the Google Index, a massive database with hundreds of billions of entries.
Not every crawled page gets indexed. Google can exclude pages from indexing if they contain duplicate content, are of poor quality, or have technical issues. Google Search Console shows the indexing status of each page.
Phase 3: Ranking
When a user enters a search query, Google searches the index for relevant pages and orders them by relevance. The ranking is based on over 200 signals, including content relevance, page authority (backlinks), user experience (Core Web Vitals), E-E-A-T signals, and many other factors.
The ranking algorithm is continuously adjusted. Google performs thousands of updates annually, including several major core updates. 2025 saw four confirmed core updates.
The AI Extension: Synthesis
Since 2024, there has been a fourth phase: AI synthesis. Google AI Overviews, ChatGPT, and Perplexity extract information from multiple indexed sources and synthesize a coherent answer from them. This synthesis layer fundamentally changes how users interact with search results.
Differences Between Search Engines
Google dominates the DACH market with over 90 percent market share. Bing holds about 4.8 percent but is strategically important because ChatGPT Search and Ecosia use Bing's index. Perplexity operates its own crawler with near-real-time indexing.
Data & Statistics
Google haelt in Oesterreich 81,87 Prozent Suchmaschinen-Marktanteil, vor Bing (9,01 Prozent), DuckDuckGo (2,75 Prozent) und Yahoo (2,57 Prozent)
StatCounter Global Stats - Search Engine Market Share Austria [Oesterreich] (2026)8,69 Millionen Internetnutzer in Oesterreich bei 95,3 Prozent Online-Penetration (Anfang 2025)
DataReportal - Digital 2025: Austria [Oesterreich] (2025)Google verzeichnet mehr als 5 Billionen Suchanfragen pro Jahr (international, Google-Konzernzahl)
Search Engine Land (zitiert Google-Blogpost) [international] (2025)69 Prozent der Desktop-Seiten nutzen ein Canonical-Tag, 45,5 Prozent ein Meta-Robots-Tag, 4,7 Prozent ein noindex (international)
Web Almanac 2024 (HTTP Archive), SEO-Kapitel [international] (2024)94 Prozent der mobilen Seiten bestehen den Viewport-Meta-Tag-Audit, aber nur 48 Prozent erreichen gute Core Web Vitals (international)
Web Almanac 2024 (HTTP Archive), SEO-Kapitel [international] (2024)E-A-T wurde im Dezember 2022 zu E-E-A-T erweitert; das zusaetzliche E steht fuer Experience (Erfahrung aus erster Hand)
Google Search Central Blog - E-A-T gets an extra E for Experience (2022)Das Ergebnis auf Position 1 hat im Schnitt 3,8-mal mehr Backlinks als die Positionen 2 bis 10; rund 95 Prozent aller Seiten haben null Backlinks (Analyse von 11,8 Mio. Suchergebnissen, international)
Backlinko - We Analyzed 11.8 Million Google Search Results [international] (2020)Das Ergebnis auf Position 1 erhaelt eine durchschnittliche organische Klickrate von 27,6 Prozent (Analyse von ca. 4 Mio. Suchergebnissen, international)
Backlinko - We Analyzed 4 Million Google Search Results (Organic CTR) [international] (2025)Google AI Overviews erreichen 2 Milliarden monatliche Nutzer (nach 1,5 Mrd. im Mai 2025); AI Mode hat ueber 100 Mio. monatlich aktive Nutzer in den USA und Indien (international)
TechCrunch (Alphabet/Google Q2 2025 Earnings) [international] (2025)GEO kann die Sichtbarkeit in generativen Suchantworten um bis zu 40 Prozent steigern (akademische Studie, KDD 2024)
arXiv:2311.09735 - Aggarwal et al., GEO: Generative Engine Optimization [akademisch] (2023)FAQ
How do search engines work in simple terms?
What is the difference between crawling, indexing, and ranking?
Which search engine is most widely used in Austria?
What does E-E-A-T mean and why is it important?
What is the difference between SEO and SEA?
How do AI searches like ChatGPT or Perplexity select their sources?
What are the most important Google ranking factors?
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