SAN FRANCISCO — Many businesses around the world could wake up on Tuesday to discover their search ranking has been downgraded. After a monthslong warning period, Google will add “mobile friendliness” to the 200 or so factors it uses to list websites on its search engine.

As a result, websites that don’t meet Google’s criteria will tumble in its all-important rankings.

Google has made several big changes. Companies will be docked for shortcomings like displaying links that are hard to click or forcing users to scroll horizontally on a lopsided site. In addition, the company recently announced that in certain cases it would also use information contained within apps as a ranking factor for mobile searches performed on phones that run its Android software.

“Since mobile search results are about half of what Google handles, anyone might be at risk,” said Danny Sullivan, the founder of Search Engine Land, which closely tracks changes to Google’s search engine.

The shift to mobile devices has been a challenge for all businesses, Google included. In the space of a few years, phones have become the dominant portal through which people use the Internet. The United States had 134 million mobile users last year, about 100 million more than in 2010, according to eMarketer, a research company.