The move is part of the social media company's efforts to attract a broader set of users, some of whom feel confined by its limits on the length of tweets as well as videos.
It's also likely to help users make money from such videos, and comes at a time when online videos are becoming increasingly widespread and popular, especially on the platforms of rivals such as Facebook.
Videos will also be longer on Vine, Twitter's video-sharing social network. Twitter said that it is starting with a "small group" of Vine creators who will "be able to add a video to their Vine, turning the six second Vine into a trailer for a bigger story."
The San Francisco company also launched an app called Twitter Engage for those it calls "influential creators." It's designed to help them interact with fans. Finally, Twitter retooled its service and Vine to make browsing for and finding videos easier. Mobile users can now tap a video tweet or a Vine to launch it in full-screen mode. Suggested, similar videos will appear below.
Digital video advertising spending in the US should reach $9.84 billion this year, up from $7.66 billion in 2015, according to research firm eMarketer. As more people watch online videos than TV, advertisers are following suit. By 2020, eMarketer expects digital video ad spending to reach $16.69 billion.
Twitter Inc currently has about 310 million monthly active users, small potatoes compared with Facebook's 1.65 billion. The professional online network LinkedIn has 433 million members, but many of these users do not log in every month.