Facebook Inc has simplified various types of advertisements on its website to eliminate confusions among marketers.The world's No. 1 social network, facebook will still display ads inside users' newsfeeds and on the right-hand side of its web pages. But it will sharply reduce the options marketers can choose for those so-called ad units.

Advertising accounts for 85 percent of Facebook's revenue, and it is trying to reinvigorate revenue growth following a sharp slowdown early last year.

With consumers increasingly accessing Facebook on mobile devices such as smartphones, Facebook has scrambled to roll out new types of ad formats suited to small mobile screens.

As part of the changes, marketers will no longer be asked to choose from a list of 27 different ad units. Instead, marketers will pick from six or seven objectives, such as driving foot traffic to a real-world store or generating "likes" for a company's page.

Facebook executives noted that marketers will still be able to select ads that run only on mobile devices or on personal computers.