When Larry Page and Sergey Brin started Google in 1995, they recognized that although existing search engines like Yahoo could help users find relevant websites, they couldn’t adequately determine which results were genuinely high quality.
Page and Brin observed that academia already had a proxy for quality: citations. A citation shows that the original work is reliable and meaningful enough to reference. When scholars publish a paper, its success is partly judged by how frequently other researchers cite it in their own work over time.
Google, therefore, built its search engine with the backlink as the digital equivalent of a citation, where more website backlinks suggest higher quality. Other search engines followed suit. Since then, search engines’ quality measure has become more nuanced, but the core principle holds: backlinks are a key indicator of your site’s quality and a cornerstone of SEO success.
Since search engines determine which websites are most relevant for people searching for specific key words, and then show the results in order of their relevance, you want to optimize your e-commerce site so potential customers can find you.
What are backlinks in SEO?
Backlinks—also known as inbound links—are links from other websites that point to your website. If your website links to another website, you’ve given them a backlink; if another site links to yours, they’ve given you a backlink. Backlinks can lead to any page on your website; they do not need to link to your homepage to be considered backlinks.
Backlinks are distinct from internal links, which are links within your site. For instance, if your homepage links to your about page, that link is internal and not a backlink.
Search engines like Google use crawlers and automated software programs that systematically browse the internet to read and understand the text on a website, known as anchor text. Crawlers follow links in the anchor text to discover new pages and content, then index the pages for the search engine. In other words, crawlers feed Google information about backlinks to your site to determine its relevance and importance for specific search queries.
Types of backlinks
Not all backlinks are equal in the eyes of a search engine. A backlink is like a vote of confidence from another site, but they don’t always count toward your quality rating. Search engines are wary of users using spam or scam tactics to earn backlinks to game the system.
Therefore, to understand a website’s quality through its link profile, search engines like Google categorize links into the following four categories:
1. Follow links
Follow links—known as such because crawlers follow them to register their value—are standard links from one website to another. For example, a golf blogger might include a link to their favorite golf stores in a blog post or another golfing blog on their “Partners” page. These are important for SEO because when a website has a follow link pointing to it, it signals to search engines that the website is trustworthy and authoritative. (If a link isn’t otherwise classified by crawlers or HTML, it’s a follow link.)
2. Nofollow links
Websites can add a piece of HTML called nofollow to their external links. This code explicitly tells the crawler that the website does not vouch for the site it’s linking to.
There are a few common reasons you might do this. Forums or social media sites nofollow their links because they can’t control what their users share. Blogs set links in their comment sections to nofollow to prevent spam sites from commenting with links in an effort to build relevance with Google.
3. Sponsored links
There are many reasons why one website would pay another for a backlink, such as for sponsored editorial content, advertisements, or paid endorsements. In these cases, search engines expect you to add a sponsored tag to your links, similar to nofollow. This tells search engines there’s a commercial relationship involved in the link, in effect telling them to disregard it. Search engines penalize, through rankings positions, sites with untagged sponsored links.
4. Spam links
As the practice of SEO has grown, so has the number of bad actors looking to boost their search rankings by gaming the system to obtain backlinks without actually earning the trust of other real websites. Search engine algorithms recognize this practice and penalize websites that do it. The most common spam links are blog comment spam and links from link farms (websites without a real following that only exist to give backlinks to other sites).
How to build backlinks
Backlinks are essential to establishing your website’s credibility and expertise within your industry. As a result, your marketing strategy should strive to generate backlinks as a secondary benefit. As more people learn about your brand, they’ll refer to your site and its content on their platforms. Here are a few specific marketing tactics that are particularly effective for link building:
1. Guest blogging
If you or your brand have specific industry expertise, sharing it on other blogs is a great way to grow your audience and earn backlinks. For example, if you run an online store for golf clubs targeted toward golfers with injuries, you might offer to write a guest blog about injury prevention in an online golf publication. This allows you to find a natural place in the article to mention your brand or add a link to your website in the author bio.
2. Broken link building
Sites that have been around for a long time often have old web pages that are no longer live. This usually happens to special promotion pages or during a website rebuild. For example, a website may have a page at the URL website.com/winter-specials that got coverage and backlinks. If the website takes down the page, they lose the value of the backlinks it gained because the links lead to a dead page. Reviewing your old pages and putting them back live or setting permanent redirect rules (301 redirects) is a great way to generate backlinks.
3. Content marketing
One of the best ways to obtain backlinks naturally—without doing outreach to individual sites—is to create and share solid informational content. Ensure your content is original, well-researched, or has a specific opinion or viewpoint. Readers will then naturally link to your site as a valuable additional resource within their content.
Suppose your golf brand writes an article titled “The Definitive Guide to Choosing the Right 9-iron” and shares it on social media. Another blogger could then come across the piece, find value, and add it to their longer article on choosing the right clubs as a helpful additional resource in the 9-iron section.
With any link building strategy, it’s essential to focus on getting backlinks from high-quality websites relevant to your site’s niche to multiple pages on your site—not just your homepage.
How to analyze backlink success
The goal of building your backlink profile is to increase your website’s search result rankings for your target keywords, leading to an increase in organic search traffic and conversions.
However, there’s no one-to-one relationship between organic traffic and backlinks. Sometimes, dozens of backlinks can lead to very little increase in traffic, while just one new backlink can produce a notable improvement. Rankings can also take weeks to change.
Therefore, on top of the so-called lagging metrics of search engine rankings and organic traffic, most SEO professionals track the following so-called leading metrics of backlink success:
- Total/new backlinks. You can track incoming links with Google Search Console, a free tool for site owners. Many SEO experts also use Ahrefs’ or STAT’s paid tools for more robust tracking.
- Domain authority, a.k.a. domain rating. While search engines themselves don’t provide a score for your backlink profile, several third-party tools give a 1–99 rating to score your backlink profile. The most common tools are SEMRush (domain authority) and Ahrefs (domain rating). These tools take in a variety of different metrics—such as traffic coming organically and traffic coming from backlinks—to determine how trustworthy your website is.
Backlinks SEO FAQ
Can having too many backlinks harm my website’s search engine ranking?
Generally, having too many backlinks doesn’t hurt your website’s rankings—as long as the links aren’t spam, which are links created to manipulate search engine rankings or drive traffic through deceptive means. Spammy links may harm your rankings. For instance, a new website getting hundreds or thousands of backlinks at once would likely register as spammy behavior.
Can buying backlinks help improve my website's search engine ranking?
No, buying backlinks from websites won’t help your rankings. Backlinks that are paid must contain a sponsored tag telling search engines to disregard them. Websites with paid links and no sponsored tags are often penalized.
Is it better to have a lot of low-quality backlinks or a few high-quality ones?
The highest-performing backlink profiles often have a mix of link types. But generally, high-quality links have a more significant impact on your search engine rankings. Think academia, where being cited in a paper by a top Harvard professor would go further than being mentioned in a first-year student’s term paper.
How can I tell if a backlink is high quality or low quality?
First, check the link type: a spammy or nofollow link—a link attribute that tells search engines not to follow or pass any ranking credit to—is immediately deemed a much lower-quality link. Then, check the backlink profile of the site providing the link. Using Ahref’s domain rating is a great way to do this. The higher the domain rating, the higher the link quality.
