SEO may generate an adequate return on investment. However, search engines are not compensated for organic search traffic, their algorithms change, and there is no guarantee of continued referrals. Due to the lack of guarantees and uncertainty, businesses that rely heavily on search engine traffic could suffer significant losses if the search engine stops referring visitors. Search engines can change their algorithms, affecting a site's search engine rankings, potentially resulting in significant traffic losses.
According to Google CEO Eric Schmidt, in 2010, Google made more than 500 algorithm changes—almost 1.5 per day. It is considered a smart business practice for website operators to move away from reliance on search engine traffic. In addition to crawler accessibility (described above), user web accessibility is becoming increasingly important to SEO.
Optimization techniques are highly coordinated with the dominant search engines in the target market. The market share of search engines varies from market to market, and so does the competition.
In 2003, Danny Sullivan stated that Google accounted for around 75% of all searches. In markets outside the United States, Google's share tends to be larger, and as of 2007, Google is still the dominant search engine worldwide. As of 2006, Google's market share in whatsapp database Germany was 85-90%. At the time, there were hundreds of SEO companies in the United States, but only about 5 in Germany. According to Hitwise, as of June 2008, Google's market share in the United Kingdom was close to 90%. This market share is achieved in many countries. You can further understand the data of global search engine share as of August 2024 .
As of 2009, there are only a few large markets where Google is not the leading search engine. In most cases, when Google is not leading in a particular market, it lags behind local players. The most notable example markets are China, Japan, South Korea, Russia, and the Czech Republic, where Baidu, Yahoo Japan, Naver, Yandex, and Seznam are the market leaders, respectively.