Updated October 2026

Link Building for SEO: What Works and What Google Calls Spam

Short answer: link building means getting other websites to link to your pages. Google uses links to find pages and as one signal of relevance, so links from real, related sites help. But Google’s spam policies define “link spam” broadly: links created “primarily for the purpose of manipulating search rankings”, which includes buying links, link swaps, automated link building and low-quality directories. The safe approach is to make pages worth citing and get them in front of people who write about your topic. Label any paid link as sponsored.

Why links matter

Google’s guide on crawlable links says it uses links “as a signal when determining the relevancy of pages and to find new pages to crawl.” A link from a page about your topic, on a site real people use, tells Google that page found yours worth pointing to. Links also bring visitors directly, which matters on its own.

Links are one signal among many. A page with great links but a weak answer to the searcher’s question still won’t hold a top position for long.

What Google counts as link spam

Google’s spam policies list these as link spam (summarized):

Buying or selling links that pass ranking credit: paying for links or posts, trading goods or services for links, or sending free products in exchange for a link.
Excessive link exchanges (“link to me and I’ll link to you”) and partner pages made only for cross-linking.
Automated programs or services that create links to your site.
Requiring a link in terms of service or a contract without letting the site owner qualify it.
Advertorials, guest posts or press releases on other sites that pass ranking credit or use keyword-rich anchors.
Low-quality directory or bookmark site links.
Keyword-rich or hidden links in widgets, and widely distributed links in other sites’ footers or templates.
Forum comments with optimized links in the post or signature.

Sites that violate spam policies can rank lower or be removed from results. The common thread: a link that exists because someone was paid or arranged it for rankings, not because a reader would want it.

How to label paid and user-generated links

Google says sponsorships and ads are fine when the link is qualified. Use these rel values on links you place for money or that users add:

<a href="https://partner.example" rel="sponsored">Our partner</a>   <!-- paid / affiliate -->
<a href="https://user-site.example" rel="ugc">...</a>               <!-- comments, forums -->
<a href="https://example.com" rel="nofollow">...</a>                <!-- don't vouch for it -->

More detail in nofollow vs dofollow links.

A realistic approach for a small site

Have something worth linking to. A free tool, original data, a clear explanation nobody else wrote, or a template people reuse. Links follow usefulness.
Show it to the right people. Writers who cover your topic, communities where your audience asks questions, and newsletters in your niche.
Collect the links you already earned. Brand mentions without a link, and broken links to pages you moved, are the easiest wins.
Skip shortcuts. Link packages, mass directory submissions and link swaps are on Google’s spam list and mostly come from sites with no readers.
Link well inside your own site. Internal links are fully in your control and help Google find and understand your pages. See internal linking and orphan pages.

The tactics, step by step, are in link building strategies.

What about spammy links you didn’t build?

Most sites collect junk links from scraper and spam sites over time. Google’s disavow documentation says that “in most cases, Google can assess which links to trust” and most sites won’t need the tool. It recommends disavowing only if you have a considerable number of spammy or artificial links and they have caused, or are likely to cause, a manual action. Check Search Console → Security & Manual Actions → Manual actions before doing anything.

Frequently asked questions

What is link building in SEO?

Getting other websites to link to yours. Google uses links to discover pages and as one signal of how relevant and trusted a page is, so links from relevant, real sites can help a page rank.

Is buying backlinks against Google’s rules?

Buying links that pass ranking credit is link spam under Google’s spam policies. Paid placements are fine when the link is marked rel="sponsored" or rel="nofollow".

Are directory links bad?

Google lists "low-quality directory or bookmark site links" as link spam. A few genuinely relevant listings (your industry’s real directory, a product launch site people use) are normal; mass submissions are not.

How many backlinks do I need?

There is no number. One relevant link from a site your audience trusts is worth more than hundreds of links from sites nobody visits.

Do spammy links pointing at my site hurt me?

Usually not. Google says that in most cases it can assess which links to trust, and that disavowing is for a considerable number of spammy links that have caused, or are likely to cause, a manual action. Check Search Console’s Manual actions report first.