Why it works
Four technical concepts explain most of what goes wrong in search visibility.
You don't need to master any of these to benefit from understanding them. This page walks through what each one means, why it matters, and what an informed question about it sounds like.
What is crawlability, and why do people talk about it so much?
Search engines use automated programs, often called crawlers or spiders, to move through the web and find pages. Crawlability describes whether those programs can actually reach and read your pages. A site can be beautifully designed and full of useful content, yet remain largely invisible if crawlers can't get through it.
Common blockers include a misconfigured robots.txt file, broken internal links, orphaned pages with no links pointing to them, and JavaScript-heavy navigation that crawlers struggle to follow. None of these require you to fix anything personally. What helps is knowing enough to ask, "Have we checked whether our sitemap includes every important page?" and understanding the answer you get back.
A useful question to bring to your developer: "Can you confirm which pages are currently blocked in robots.txt, and why?"
Why do site speed reports seem to contradict each other?
Site speed is measured in more than one way, and that's where a lot of confusion starts. Lab data, gathered in a controlled test environment, can show a different score than field data, which reflects how real visitors actually experience the page on their own devices and connections.
Core Web Vitals measure specific aspects of loading, interactivity, and visual stability. A page can score well on one metric and poorly on another, and a single low score doesn't automatically mean the site is broken. Understanding this distinction helps you avoid reacting to every fluctuating number, while still knowing when a persistent, significant drop is worth raising with your team.
A useful question to bring to your developer: "Is this score based on lab data or real user field data, and has it been consistent over the past month?"
What does structured data actually do for a website?
Structured data, often implemented as schema markup, is a standardized way of labeling information on your page so that search engines can understand its meaning more precisely. A recipe page can mark up ingredients and cook time. A local business page can mark up hours and address. This labeling can influence how a listing appears in search results, though it doesn't guarantee any particular placement or feature.
After a site redesign or platform migration, structured data is one of the things most likely to break quietly. Pages can look fine visually while the underlying markup has been stripped out or duplicated. Knowing that structured data exists as a separate, checkable layer helps you ask for it to be verified specifically, rather than assuming a visual review covers everything.
A useful question to bring to your developer: "Can we run the updated pages through a structured data testing tool before this goes live?"
If a page is crawled, does that mean it's indexed?
Not necessarily, and this distinction confuses a lot of site owners. Crawling is discovery. Indexation is the decision to store and potentially show that page in search results. A page can be crawled repeatedly and still sit outside the index, for reasons ranging from thin content to a duplicate canonical tag pointing elsewhere.
Pages sometimes drop out of the index after a migration, a content update, or an accidental noindex tag left in place from a staging environment. Understanding this two-step process means you won't assume "it's live" automatically means "it's searchable," and you'll know to check indexation status directly rather than guessing from the page simply loading in a browser.
A useful question to bring to your developer: "Has anyone checked whether this page is actually indexed, not just live and crawlable?"
A quick reference
Four concepts side by side
| Concept | What it governs | A sign something may be off |
|---|---|---|
| Crawlability | Whether search engines can reach a page at all | Pages missing entirely from search, even by exact title |
| Site speed | How quickly and smoothly a page loads and responds | Consistently poor Core Web Vitals scores over weeks |
| Structured data | How clearly page content is labeled for machines | Rich results disappearing after a redesign |
| Indexation | Whether a crawled page is stored in the search index | A live, working page that never appears in search |
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