In their study of Twitter’s “contagion process,” the team looked at data from 16,000 U.S. cities, focusing on the 408 with the highest number of Twitter users and seeking to update traditional models of how information spreads and technology is adopted. Just as marketing experts sometimes label consumers as early adopters, early majority adopters, late majority adopters or laggards, the researchers characterized cities in those terms, based on when Twitter accounts in a given city reached critical mass. Critical mass is generally defined as the point when something reaches 13.5 percent of the population, which for this study was 13.5 percent of the highest total number of Twitter users in a city through August 2009, the end of the study period.

As with most technologies, the growth in popularity initially spread via young, tech-savvy “innovators,” in this case from Twitter’s birthplace in San Francisco to greater Boston. But the site’s popularity then took a more traditional route of traveling only short distances, implying face-to-face interactions. This approach made early adopters of Somerville and Berkeley - cities close to Boston and San Francisco, respectively. Twitter use then spread through early majority cities such as Santa Fe and Los Angeles and late majority cities such as Baltimore and Las Vegas before reaching laggards such as Palm Beach and Newark. All these cities ultimately ranked among the 408 nationwide with the largest numbers of Twitter accounts.

“Even on the Internet where we may think the world is flat, it’s not,” says Marta González, assistant professor of civil and environmental engineering and engineering systems at MIT, who is co-author of a paper on this subject appearing this month in the journal PLoS ONE. “The big question for people in industry is ‘How do we find the right person or hub to adopt our new app so that it will go viral?’ But we found that the lone tech-savvy person can’t do it; this also requires word of mouth. The social network needs geographical proximity.”

For nearly 50 years, marketers have studied the “diffusion of innovations” (named by Everett Rogers in his 1962 book of the same title) to predict how the purchase of expensive, durable goods such as cars and refrigerators will spread. But the diffusion of high-tech websites and cheap smartphone apps is thought to occur in a very different way.

“Nobody has ever really looked at the diffusion among innovators of a no-risk, free or low-cost product that’s only useful if other people join you. It’s a new paradigm in economics: what to do with all these new things that are free and easy to share,” says MIT graduate student Jameson Toole, a co-author of the paper.

Meeyoung Cha of the Korea Advanced Institute of Science and Technology is the third co-author, and also the person who had the prescience to begin downloading Twitter-published user data (via Twitter API) in May 2006, when there were only a couple of hundred users. She downloaded data through August 2009, when user growth dropped off for a time. González and Toole said their model of Twitter contagion didn’t fit Cha’s data until they added media influence, based on the number of news stories appearing weekly in Google News searches, data they acquired using Google Insights for Search, which provides historical search-engine data.

“Other studies have included news media in their models, but usually as a constant,” González says. “We saw that news media is not a constant. Instead, it’s media responding to people’s interest and vice versa, so we included it as random spikes.”

The study data include the growth spike that began April 15, 2009, when actor Ashton Kutcher challenged CNN to see who could first attract 1 million Twitter followers. Kutcher ultimately won, reaching the million mark in the wee hours of April 17, about half an hour before CNN. Popular talk-show host Oprah Winfrey invited Kutcher to appear on her show that same day; when she ceremoniously sent her first tweet, the pace of new news stories picked up again, and so did new Twitter accounts.

The Twitter bird was suddenly on all the wires, and Twitter’s user accounts increased fourfold because of the media attention, indicating that as recently as 2009, location-based social networks and media attention still held sway over computer-based social networks. Photo: www.imagine-your-world.com

Launched on July 15, 2006, the San Francisco based company has about 100 million active users, generating over 300 million tweets and handling over 1.6 billion search queries per day. As a social network, Twitter revolves around the principle of followers. Users that follow other users will see their tweets in reverse chronological order on the Twitter homepage. The site allows users to group posts or topics by using hashtags. While the social networking site redesigned its website several times since its launch and added other services such as Twitter Lists (ad-hoc lists), it managed to keep its service remarkably simple: messages are still limited to 140 characters.

Bin Talal, nephew of King Abdullah of Saudi Arabia, used Kingdom Holding to invest in Twitter. With personal assets topping an estimated $21 billion, Forbes magazine ranks the prince as the 26th richest man in the world. He also owns stakes in blue chip companies including Apple, Citigroup, and General Motors.

"As a first cut, we implemented support for Facebook, Twitter, and email via Gmail," says Mozilla on its Lab blog. "We picked those because they’re popular, have good API support for authorization using OAuth, and in the case of GMail, provide APIs to contacts, which makes for a good auto-complete experience."

Mozilla says that it plans to extend F1 functionality to support more sharing services if they advertise to the browser and offer a sharing API. Publishers can use an experimental share API to the navigator object. The feature allows website owners to add share buttons to specific items within the page. When a user wants to share the content, the F1 share panel will open.

The success of F1 will eventually depend on whether Mozilla incorporates the extension into its Firefox browser or continues to offer it as a downloadable add-on. More information about F1 and a short video explaining how the extension works is available here. The site contains a link that allows users to download the extension.

"Online communication tools are an important part of people's lives--whether they're connecting with their friends and family, sharing pictures and videos, or keeping up on news across social networks," said Blake Irving, chief product officer, Yahoo. "We've built a powerful global framework for email that lets us quickly innovate and enhance this trusted service that people rely on every day. Yahoo Mail Beta completes our trio of mail experiences, seamlessly spanning the PC, Droid, iPhone and iPad. For the millions of people who access email from a PC and a phone or tablet, there's no better cross-device experience."

The new mail service has been redesigned from the ground up to allow for more efficient communication. It will be at least twice as fast as the previous version, Yahoo says. Upgrades include tools to organize, prioritize and search mail. An improved spam filter will help to provide a safer email experience while an automatic slideshow feature allows users to see photos and videos from sites like Flickr, Picasa, and YouTube within their email messages.

Users who decide to opt in should expect frequent updates and changes during the beta service that is now available in 25 markets around the world.  A Yahoo website explains how the new features work.

It’s all about speed and social networking – Yahoo introduces the first major overhaul to its mail service since 2005. Photo: www.imagine-your-world.com

After signing up for the free service, users can search for friends that are using the application and follow them like on social networks. They have the option to attach location information to any post via the Foursquare API, and upload an unlimited number of photos. Instagram allows users to upload and share pictures on Flickr, Twitter, Tumblr, and Facebook. Friends and followers can be imported from the iPhone contact list or Facebook and Twitter. "I have been waiting for this for a while now and I'm exceedingly happy for the results," says Andres Henry on the iTunes preview webpage.

The Instagram website advertises the free services as a "… fast, beautiful and fun way to share your life with friends through a series of pictures. Snap a photo with your iPhone, choose a filter to transform the look and feel … it’s all as easy as pie. Its photo sharing reinvented."

The current version 1.0 was released on October 6, 2010.