Technical SEO is the work that decides whether a search engine can find a page, read it, and treat the right URL as the one to show. It sits underneath everything else: a page that cannot be crawled, renders empty, or points its canonical at a different address does not compete, however good the writing is.
The parts, in the order they usually fail
Crawling
A crawler has to reach a URL before anything else can happen. robots.txt controls crawling, not indexing: a disallowed URL can still appear in results without its content, and a noindex tag only works if the crawler is allowed to fetch the page and read it. Internal links are how most pages are discovered; a sitemap is the safety net underneath.
Indexing
Crawled is not indexed. Search Console's page indexing report separates "crawled — currently not indexed", "duplicate, Google chose a different canonical", "excluded by noindex" and soft 404s, and each has a different cause. I go through them in the Search Console reports worth opening.
Canonicalisation
Every page should have one address. rel="canonical" is a strong hint rather than an instruction; a 301 redirect is stronger. This site redirects /seo/index.html to /seo/ for exactly that reason.
XML sitemaps
A sitemap should list canonical, indexable URLs that return 200 — not redirects and not noindex pages. One file holds up to 50,000 URLs or 50 MB uncompressed. Having one is not the same as it working: across 34 Nepali websites the median sitemap listed 14 URLs (the sitemap study).
Structured data
JSON-LD describes what a page is — an article, its author, an organisation — in a form machines can read without inferring. It must describe content that is visible on the page. It makes a page eligible for some search features; it is not a ranking boost. Which types are worth adding.
Rendering and JavaScript
Google renders JavaScript, but content that only exists after a script runs is content that can fail to exist. Server-rendered HTML is the safe default. It is not a theoretical risk: this site once served empty pages for days because a script arrived as zero bytes (what happened).
Core Web Vitals
Three field measurements of real visits: Largest Contentful Paint (good at 2.5 seconds or less), Interaction to Next Paint (200 milliseconds or less; it replaced First Input Delay in March 2024) and Cumulative Layout Shift (0.1 or less), each assessed at the 75th percentile of page loads. Google's ranking systems use them, but relevance still comes first. Source: web.dev.
Status codes and redirects
A missing page should return 404, not a 200 that looks like an error. A permanent move should be one 301 to the final URL, not a chain. Moving a site without losing search traffic.
A technical audit, in order
- Do the important URLs return 200?
- Are they indexable — no stray
noindex, no robots block? - Does each declare itself canonical, and do internal links point at that address?
- Is the main content present in the raw HTML?
- Does the sitemap list what the site actually contains?
- Is the structured data valid and accurate to the page?
- How do the pages behave on a mid-range phone on mobile data?
What 34 Nepali websites showed
| Check | Result |
|---|---|
| No H1 at all | 14 of 34 |
| No canonical tag | 12 of 34 |
| No structured data | 16 of 34 |
| No findable sitemap | 10 of 34 |
| Median time to first byte | 849 ms |
Sample, dates and method: the 34-site technical audit and the research section.
