Twitter use is growing as some 13 percent of online adults surveyed said they use the microblog, which lets people update their status in 140-character messages called tweets.
Pew Research said Twitter use saw a "significant increase" from the 8 percent of online adults who said they used Twitter last November.
Twitter surveyed 2,277 online adults 18 and older via phone in English and Spanish between April 26 and May 22, 2011. Pew said 95 percent of Twitter users said they own a mobile phone, with 54 percent of these users tweeting from their handsets.
Just as in the November study, Pew found that Twitter use among African Americans and Latinos is high. Some 25 percent of African Americans Web users employ Twitter at least sometimes, compared with just 9 percent of white Web users who said they use the service. Also, 19 percent of Latinos surveyed said they use Twitter.
Moreover, Twitter is predominantly used by younger Web users. Nineteen percent of people aged 25 to 34 claimed they use Twitter, up from 9 percent in late 2010. Also, 14 percent of users aged 35 to 44 said they use Twitter, up from 8 percent last year.
Twitter is believed to command something in the range of 200 million users, though the microblog won't confirm those numbers due to all of the people who use the service from third-party mobile clients.
Twitter CEO Dick Costolo said at the D9 conference June 1 that Twitter users were pumping out 1 billion tweets every six days. Costolo also said there are over 600,000 Twitter developers.
To help boost growth, Twitter unveiled new features this week. At D9, Costolo unveiled Twitter's new photo-sharing service, which is powered by PhotoBucket.
Over the next few weeks, Twitter users will be able to upload a photo and attach it to their tweet right from Twitter.com, as well as Twitter's official mobile applications. Twitter also said it improved its search engine to surface photos and videos in addition to tweets.
A day earlier the company launched the Follow Button on more than 50 sites to let users find and follow Twitter accounts of media reporters, athletes, celebrities and others with a single click.
Users can also see the profile and latest Tweets of the account they want to follow by clicking the user name next to the Button.
Twitter partners such as AOL.com, Britney Spears, CBS Interactive, CBS News, cnet.com, CNNMoney, Jennifer Lopez, Lady Gaga and others are embedding the Follow Button, whose code may be found here.
Twitter's Follow Button will be compared with Facebook's Like Button, which launched last year, and Google's +1 button, which also launched today.