What Can Be Sold in 140 Characters? That’s Now the Challenge for Twitter

So get ready, Twitter users: you are going to see more ads in your message stream, especially if you live overseas.

You may also see Twitter become more like a flash-sale site, with offers to buy products appearing in your message stream along with a way to buy them with a quick click or tweet.

In documents filed on Thursday to inform investors ahead of its initial public offering of stock, Twitter noted that it has been greatly expanding its inventory of advertising slots, especially for promoted tweets, which are sponsored messages that use the same format as the 140-character postings, or tweets, that are the core of the service.

The company, based in San Francisco, said that across its base of 218 million users, the average person is checking the service more frequently — about 230 times a month, compared with 197 times a month a year ago. And users are also interacting with more ads.

But Twitter revealed that it has also significantly increased the number of ads it sells, and prices for those ads have fallen. The company said it believes cheaper, more targeted ads will draw in more advertising, more than making up for the price drop.

So far, the strategy seems to be working — the company said advertising revenue more than doubled in the first six months of this year, to $221 million, compared with the same period last year.

Joy Baer, executive vice president of Strata, which makes software that helps advertisers and ad agencies buy online ads, said that the 1,000 ad agencies that use Strata had been rapidly increasing their purchases of Twitter ads over the last two years. Although Facebook still dwarfs Twitter in overall revenue, she said that for every $100 in Facebook ads her customers buy, they are buying $33 of Twitter ads.

“There is a huge opportunity for them to get more of the dollars,” Ms. Baer said. “What they have to do is make it easier for a media buyer to click a button and buy Twitter.”

Right now, the company’s ad-buying process is less automated than for competitors like Facebook and Google.

Twitter declined to comment, citing regulations limiting what a company selling stock to investors could say beyond its official filings.

But analysts say that Twitter faces several growth challenges.

More than three-quarters of the company’s users are outside the United States, and it must find a way to make money from those global users. Right now, only 25 percent of its revenue comes from overseas. In the second quarter of the year, each American user represented about $2.17 in ad revenue to Twitter. Each one outside the United States brought in about 30 cents during the quarter.

Twitter’s big challenge is to convince a company outside of the United States why it should spend advertising money with Twitter, and not with other outlets, said Daniel Knapp, director of advertising research at the consultant IHS Screen Digest in London.

Twitter also has limitations as a medium, compared with more visually robust services like Facebook or Google, which can also count on revenue from video and display ads. And the competition isn’t standing still — Instagram, a fast-growing photo sharing service owned by Facebook, announced on Thursday that it would begin putting ads in the photo feeds of its users, something that advertisers have been eagerly awaiting.

Although Twitter has struck deals with television networks in the United States and some other countries to run video clips that are sponsored by advertisers, those are still a small proportion of revenue compared with its sponsored tweets.

The company’s robust presence on mobile devices — 75 percent of its users access the service that way, and two-thirds of revenue is from mobile ads — can also be a limitation where smartphones are not common.

In India, for example, Twitter is widely used by Bollywood stars like Amitabh Bachchan, who has 6.5 million followers on the service.

The service has also become one of the most important platforms for political debate there.

David Jolly and Mark Scott contributed reporting from London and Peter Eavis and Jenna Wortham from New York.

The Getaway: A Hotel Room With 140 Characters

Then came the “digital detox” vacation — the no-cellphones, no-Internet-allowed response to increasingly inescapable and seemingly addictive technology.

Now comes the backlash (or at least the appearance of one). The first “Twitter experience hotel” (a k a Sol Wave House) was introduced this summer in Majorca, Spain, where guests can ping requests to a “Twitter concierge” using hashtags like #fillmyfridge; flirt from poolside Bali beds by tweeting numbers printed atop the beds, like “How’s it going #balibed10?”; and sip cocktails while checking their smartphones for a live feed of virtual conversations bubbling up from every corner of the hotel.

Meliá Hotels International, which owns more than 350 properties, including Sol Wave House, is pioneering the concept amid the still rising popularity of smartphones and social networking. The Internet is in more pockets today than ever before. In July the International Data Corporation, a research group, said the worldwide smartphone market experienced 52.3 percent year-over-year growth. (In the United States, 56 percent of adults own a smartphone, up from 35 percent in 2011, according to the Pew Research Center’s Internet and American Life Project surveys.)

The number of people on social networking sites is also growing. About 1.3 billion people worldwide are now using social networks (that’s about 82 percent of the global Web population), up from about 1.2 billion last year, according to comScore.

Sol Wave House was refurbished two years ago, but the Twitter theme — the “share the love” signs at the front desk, the Twitter suites and concierge — is new.

“The social night-life scene is significant, so we already had a ripe environment that we were looking to augment,” said Tony Cortizas, vice president for global brand strategy of Meliá, which is based in Palma de Mallorca. The hotel itself is shaped somewhat like an amphitheater, with rooms and balconies that allow guests to peer down at public areas with pools, daybeds, wave machines and D.J.’s. “The clientele coming in are younger,” Mr. Cortizas said.

And according to the Pew Research Center, which has been conducting one of the more thorough studies of Twitter, Internet users ages 18 to 29 in the United States are the most likely to use the network, making a Twitter theme hotel a distinct way to speak with that demographic.

Mr. Cortizas said he marvels at how young people are living today. “It’s so completely normal for someone to be looking down on the street and walking into people because they’re looking at their device,” he said. “For the generations that are literally growing up that way, it’s really normal.” Sol Wave House is striving to “bring what is normal and every day for these guys and give them a sandbox to play in.”

That sandbox includes a Twitter concierge that guests can instruct via tweet to “Get the Cava on ice” followed by “1 bottle, 4 glasses to the solarium,” as one visitor did last month. There are images of mustaches on mirrors in the rooms, encouraging guests to tweet goofy selfies. And on Friday afternoons at the height of the season, the concierge uses a pool party hashtag (#twitterpoolparty) to summon sun worshipers.

To create a measure of privacy, all virtual interactions take place within an internal community available only to guests through an app and the hotel’s free Wi-Fi. Upon signing in with their personal Twitter accounts, guests can see who else is online, and send virtual kisses to one another. A recent peek behind that digital curtain showed guests uploading photos of their burgers, asking the concierge if there were any Russians visiting the hotel (there were) and participating in online contests.

“In our business,” Mr. Cortizas said, “rooms are rooms and suites are suites, but in the end it’s always about what you are doing to deliver an experience to a customer. We were looking to try and do something that would differentiate us, and we were trying to do something that would be kind of fun.”

So why Twitter? What about that other prominent social network? For one thing, competitors are already using Facebook to attract travelers. Take Ushuaïa Ibiza Beach Hotel, owned by the Palladium Hotel Group, which enables guests to instantly update their Facebook status by swiping their fingers on sensors around the grounds.

Mr. Cortizas said the other major reason for emphasizing Twitter is that it is especially popular in Europe, from which Sol Wave House draws many guests.

140 Characters Spell Charges and Jail

“Let’s Go Kill the President,” wrote Mr. Britton, who is 26 and unemployed. “I think we could get the president with cyanide! #MakeItSlow.”

When Secret Service agents showed up at his house to question him, Mr. Britton said he had been drunk and apologized. But in September, he posted another round of death threats against President Obama and was arrested. Last month, he was sentenced to a year in federal prison.

“Because of the repeated threats on Twitter, we took him seriously,” said Joyce White Vance, the United States attorney for the Northern District of Alabama, who prosecuted the case.

Mr. Britton was the latest in a recent series of social media users to overstep the boundary of legal free speech and face jail time for threatening the president’s life. Last month, a Twitter user in Charlotte, N.C., Donte Jamar Sims, was sentenced to six months for posting “Ima assassinate president Obama this evening!” among other threats. And Daniel Temple of Columbus, Ohio, is awaiting sentencing for saying on Twitter that he was “coming to kill” the president and “killing you soon.”

A Secret Service spokesman, Brian Leary, said social media are increasingly useful for finding and tracking threats. In 2011, the agency created the @SecretService account, to let users report suspicious tweets. And a group of agents, called the Internet Threat Desk, focuses specifically on threats posted online.

“We get information from many sources. Social media is one of them,” Mr. Leary said. “We have the right and certainly the obligation to determine a person’s intent.”

The Secret Service investigates an average of 10 threats against Mr. Obama each day, roughly the same number as during George W. Bush’s administration, said Ronald Kessler, author of “In the President’s Secret Service,” a book about the agency. The agency would not confirm that number and does not say how many threats it receives and turns over to the Justice Department to prosecute.

But privacy advocates worry that remarks intended for friends and followers may be misinterpreted in a courtroom or that carelessly typed posts will be seen in the same light as letters mailed to the White House.

“Twitter makes it easier for people to say things they don’t mean seriously and be broadcast far and wide,” said Hanni Fakhoury, a staff lawyer for the Electronic Frontier Foundation, a privacy advocacy group. “If I say online that I want to kill Obama, it’s far harder to assess how serious I am than if I’m standing across the street from the White House and I have a gun.”

Federal law makes it punishable by up to five years in prison and a $250,000 fine to threaten the life of the president or anyone else under Secret Service protection. The law does not require proof that the suspect intended to carry out the plot.

Ms. Vance, the prosecutor, said the case against Mr. Britton was clear cut: He had posted two rounds of threatening messages and ignored the Secret Service’s initial warning.

Mr. Britton, who is in prison, could not be reached. But his lawyer, Rick Burgess, said Mr. Britton had no actual plans to harm the president. Court records show that Mr. Britton has received medication for schizophrenia.

A spokeswoman for Twitter did not reply to requests for comment about whether the company removes death threats from the site or provides the Secret Service personal information about users accused of threatening the president. Court records show that in Mr. Britton’s case, a woman saw his messages, alerted the Secret Service and agents found his home address.

The Justice Department does not say how many threats against the president have been prosecuted, according to a spokesman.

Last year, a college student in Florida said he was joking when he posted on Facebook about killing the president during a trip to the University of Miami. “Who wants to help me assassinate Obummer while hes at UM this week?” the student, Joaquin Serrapio, asked. He later was charged with threatening to harm the president, a felony. He pleaded guilty and received three years’ probation.

In another case, Walter Bagdasarian of San Diego said he was drunk when he posted a rant on his blog saying the president “will have a 50 cal in the head soon,” referring to a .50-caliber rifle bullet. In federal court, he won an appeal by arguing that his comment stopped short of being a threat.

The cases based on such threats should be a reminder that there are limits on the First Amendment’s protection of free speech, said Mr. Burgess, the defense lawyer. “Whether you meant it as a joke or not,” he said, “a Twitter message takes on a whole new meaning when it’s read in a courtroom.”