Twitter

Twitter is expanding the features of its apps and website yet again, this time adding group messages and 30-second videos.

In November, Twitter said it would create a way for people to privately send messages to groups -- instead of just to individuals -- as well as expand its video offerings. Starting Tuesday, those features will be available to customers on most devices, including those from Apple and those powered by Google's Android operating system.

The refinements come as fears continue to build about Twitter's ability to expand both its number of users and their activity while also attracting advertisers. The company has grappled with inconsistent user growth, most recently tallying 284 million users who logged into the site at least once a day in the third quarter -- a 23 percent jump from a year earlier.

Investors, who aren't convinced that Twitter can keep boosting user growth, have pushed down the company's stock more than 35 percent over the past year.

By letting people shoot, edit and post their own videos from within the Twitter app, the company has a potential to both attract advertisers and increase usage of its platform. Twitter focused its engineering efforts on making it as easy as possible for people to shoot and share video, said Jinen Kamdar, a product director the social network.

"We are optimizing for quick and instant sharing," he said.

Twitter bought video-sharing service Vine in 2012. Vine, a standalone app, has gained millions of users by letting people post six-second videos.

Twitter

The expanded direct-messages feature will make it easier for groups of people to communicate privately, Kamdar said. Facebook has similar features focused on connecting friends and family. Twitter's offering differs by allowing its users to remain anonymous.

"The thing that makes Twitter unique is that the people you interact with are people you may not know," Kamdar said. Having the capability to communicate in chats away from the public stream will appeal to some users.