When to go multilingual (and what hreflang actually does)

When multilingual makes sense

Adding another language to your site is a content and technical commitment. Do it when you have a real audience who need information in that language, not just because it sounds good.

• Legal or policy: Welsh and English for public sector in Wales; bilingual requirements for some charities or funders.
• Audience: You serve people who prefer or need content in another language (e.g. local communities, international clients).
• Search: People are already searching for what you offer in that language, and you want to be found.

If you are only translating a handful of pages or a single campaign, consider a simpler approach (e.g. a dedicated landing page) rather than a full multilingual site.

What hreflang is for

hreflang tells search engines which language and region version of a page exists, so they can show the right version in the right search results [1]Source 1 .

It does not translate your content. It does not change what users see when they land on the page. It only helps search engines match queries to the correct language variant.

When you need it

• You have the same or similar content in more than one language (e.g. English and Welsh, or English and French).
• You want search engines to show the Welsh version to Welsh queries and the English version to English queries, instead of picking at random or showing duplicates.

When you can skip it

• Only one language on the site.
• Truly separate audiences with no overlapping content (e.g. a completely different site per region).

How hreflang works (plain version)

For each page that has language variants, you declare: “This page is available in these languages, and here are the URLs.”

• In the HTML: You add link tags in the head with rel="alternate" and hreflang="xx" (e.g. en, cy for Welsh), pointing to the full URL of each variant.
• Include every variant: Each version of the page (e.g. English and Welsh) should list all versions, including itself.
• Use the right code: Language codes follow ISO 639-1 (e.g. en, cy). For region-specific variants you can use en-GB, en-US.

Search engines use this to group variants and choose which one to show in which search result.

Common mistakes

• Missing or wrong URLs: Each hreflang link must be a full, absolute URL. Broken or relative URLs are ignored or can cause wrong indexing [1]Source 1 .
• Only one side linked: The English page must link to the Welsh page, and the Welsh page must link to the English page (and list both on both). If pages do not point to each other bidirectionally, the tags are ignored.
• Mismatched content: If the “Welsh” URL actually shows English, or a different page altogether, you confuse users and search engines.
• Using x-default: hreflang="x-default" is optional. Use it to point to the default version when no other language or region matches. Often that is your main language (e.g. English). Do not set x-default to a “choose language” page unless that is genuinely the intended default.

What to do first

1. Decide which pages have language variants (e.g. homepage, key service pages, contact).
2. Ensure each variant has a stable, canonical URL (e.g. /cy/ for Welsh, or /welsh/ if that is your convention).
3. Add hreflang link tags in the head of each variant, pointing to all variants with the correct language codes.
4. Check in Google Search Console that the alternate URLs are recognised and that you do not have duplicate-content or redirect issues.

For more on technical foundations, see technical SEO: the foundations that matter and website structure: organising pages for users and search.

Summary

Go multilingual when you have a real need and the capacity to maintain quality in each language. Use hreflang so search engines can show the right language to the right user. Implement it with full URLs, on every variant, and keep content and URLs in sync.