Facebook has revamped its design, making its website look more like its Android and iOS mobile apps.
The refresh also introduces topic-specific alternatives to its news feed.
One consequence of the change is that adverts can take up more screen space, making them harder to ignore.
However, the project's lead engineer denied ads were the redesign's focus. He also played down suggestions that the move was intended to make people spend more time on the site.
Chris Struhar instead suggested his focus had been on stripping back the amount of information being shown on the news feed to make each post more "engaging".
Facebook is selling the new version of newsfeed under the catchline "Goodbye clutter", insisting that it is about making the user experience better rather than boosting its advertising revenue. But if it works for users, it will make the social network more valuable for advertisers too.”
Facebook reported in January that 1.06 billion people were using its service at least once a month.
It also revealed that its profit for the last three months of 2012 was 79% down on the same period the previous year despite a rise in sales because of increased spending on research and development.