The Lumina SEO blog: expert analysis on search engine optimization, generative engine optimization, and the evolving AI search landscape.
What AI visibility means, the four metrics worth tracking, and why a rank number is the wrong answer. Live audit across ChatGPT, Claude, Gemini and Perplexity: turning on web search costs up to 24 times an ungrounded call, Gemini never names the publisher it cites, and in German AI Overviews YouTube outranks every SEO vendor with 3,118 citations.
What Google and Bing actually do with sitemap fields, the five sitemap variants, how to handle lastmod, submission via Search Console, Bing and IndexNow, and what's known about AI crawlers.
What Google documents about images: alt text, WebP and AVIF, the right loading pattern for the LCP image, license metadata, and what's actually known about images in AI search.
What Google documents about E-E-A-T, why it isn't a ranking factor on its own, what's actually known about AI search, and how to make experience, expertise and trust visible on a page.
How RFC 9309 reads a robots.txt, which AI crawler user-agents exist and which of them actually follow the file, five patterns that work and six common mistakes.
What Google actually documents about internal links, five linking patterns that work, six common mistakes, three ways to audit, and what AI search does and doesn't change.
When keyword cannibalization is a real problem, how to confirm it in Search Console, which fix fits which pattern (including pagination and filter URLs) and how a keyword map prevents it.
How Google renders JavaScript, which rendering mode to pick for SEO, and why client-side rendering hurts more in 2026: the crawlers behind ChatGPT, Claude and Perplexity don't run JavaScript at all.
AI text doesn't fail because GPTZero catches it. It fails because readers notice the patterns it ships with. The 8 patterns to fix, the German-specific ones, and when to ship as-is.
The directories that still count, how to keep your NAP consistent, what changed at Apple and Foursquare, and what to skip.
Every field that matters, how verification and appeals work, and what changed after Google removed Q&A. Checked against Google's own help pages.
The three factors Google actually ranks by, the review numbers that separate the 3-pack from position 7, and the myths that waste your budget.
LCP, INP, CLS — what they measure, what counts as good, why PSI and Search Console disagree, and how to fix each metric.
The types, the code, the validators, the mistakes, and which rich results Google still shows after removing Course info, FAQ and more in 2025 and 2026.
PageSpeed Insights for 50 large DACH news sites, re-measured with field data in September 2026: 36 of 47 pass Core Web Vitals for real users, while the median mobile lab score is 52.
Every major AI bot, which ones follow robots.txt, and a live audit of 10 top news sites: 9 of 10 block ClaudeBot, and OpenAI's search bot gets through more often than Anthropic's.
Does structured data get you cited by ChatGPT, Perplexity or AI Overviews? What Google documents, what a controlled Ahrefs study found, and which schema is still worth adding.
50 DACH media tested for JS rendering. Seven hide 25 %+ of their content from AI crawlers. News.at shows 100 % only after JS runs — classic AI crawlers see a blank.
Robots.txt of 50 large DACH media sites, re-measured in September 2026: 69% block OpenAI's training bot, 18% its search bot, none block Googlebot.
Three optimization disciplines, one web. SEO chases blue-link rankings. AEO wins direct-answer queries. GEO gets cited inside generative AI. Here is how they differ and how they stack.
Practical SEO for ChatGPT, Perplexity, Gemini and AI Overviews, limited to what Google, OpenAI and published studies actually document.
GEO optimizes content to be cited inside ChatGPT, Perplexity, and Google AI Overviews. SEO optimizes for blue links. Here is the honest breakdown of what changed and where each one wins.
Google documented a 2 MB limit per file for Googlebot, HTML, CSS and JavaScript alike. What that means, who's actually affected, and how to check your own pages.
Confirmed dates, Sistrix winners and losers in Germany, the May core update that followed, and the claims about this update that Google never made.
Google shut down Project Mariner in May 2026. Google-Agent stayed, and it generally ignores robots.txt. What that changes for your site.
Lumina's SEO blog covers the stuff I actually work on day to day: Google algorithm updates, the shift from classical SEO to GEO (generative engine optimization), AI crawler behavior, and the practical tools you need to keep up. No repackaged press releases or recycled tips. Every post is based on my own research or something I tested myself before writing about it.
My filter is simple. If I had to explain something to a client and couldn't find a clear write-up to send them, that's a post. Most articles here started as an email I drafted twice.
For the same content, the format makes a big difference. Blogs are the best fit for technical topics that need code snippets, diagrams, links, and reference tables you can copy. Newsletters win when the value is an opinion or a curated list delivered regularly. Podcasts are best for interviews and the kind of context you can't compress into bullet points. I stick with the blog format here because most SEO topics need exact syntax and screenshots to be useful.