Google Quality Score

The quality score is at once one of the most important and one of the least understood components of a successful Google AdWords campaign. Everything from your position on a search results page to your actual bid depends on your quality score, and yet the precise algorithm used to calculate it is a closely guarded secret. There are a variety of theories about what matters most to a high quality score. Click-through rate (CTR)? Keywords in your ad copy? A quick-loading landing page?

We’ll get into known quality score factors over the next few tutorials, but there is one overriding theme you should always keep in mind: Quality Score is a measure of relevance.

Though Google AdWords is far and away the dominant search advertising platform in the world today, it wasn’t the first pay-per-click platform. That honor goes to In a 1998 article for The Search Engine Report, Danny Sullivan described GoTo’s then-new model: “Advertisers can open accounts and bid on how much they’ll pay to appear at the top of results in response to specific searches. Advertisers are currently paying anywhere from one cent to one dollar a click, GoTo says.” The top-paying advertiser got the top spot. The model worked so well that Bing Ads and Yahoo both used it to fuel their own nascent search advertising programs. By 2003,, now called Overture, was acquired by Yahoo.

As successful as GoTo was, there was a significant flaw in its logic: the highest-paying advertiser isn’t necessarily the highest-quality advertiser. Once enough users clicked on an ad expecting t-shirts, electronics, or wedding gifts — only to find low-priced pharmaceuticals or some other irrelevant offering — clicks, and therefore revenues, would drop off significantly.

Enter Google. Beginning in 1998, Google introduced the PageRank algorithm (named for Google co-founder Larry Page) to organize its search results. This proprietary algorithm assigned importance to websites based on a variety of factors ― especially links from other sites (i.e., votes of confidence from other users). The higher a site’s PageRank (or “importance”), the higher it would show up in organic search results. With that innovation, Google revolutionized online search.

Google quickly became one of the hottest startups in history, but still wasn’t generating much revenue. The next revolution came when it introduced quality score. Just as PageRank assigned “importance” to websites, Google’s quality score assigned “relevance” to search marketing ads. The higher an ad’s quality score (or relevance) the higher it would show up in paid search results. This provided users with the offers they were looking for, and advertisers with the customers they were seeking. Keyword bids were still crucial, but no longer the only factor.

Keeping that background in mind helps you be a significantly more effective search marketer.  Rather than thinking of quality score as an abstract, black-box algorithm, think about it as a brilliant solution to a clear business problem: how to deliver the most relevant ads. Over the next few tutorials, we’ll discuss how to make your ads as relevant as possible. We’ll cover broad points such as copywriting and keyword alignment, as well as more specific quality score tips about maximizing quality score over the life of your Google Adwords campaign.

But first, it’s important to know precisely how quality score affects your costs and revenues.