CAPTCHA - Telling Humans and Computers Apart Automatically

You may have received requests from known friends to join a social network.

Social networking sites employ a program called Captcha — as do many other sites to stop fraudsters from creating thousands of email IDs and then sending spam.

Captcha, which distorts the letters of a word in a way that can be identified only by a human, is widely employed by many companies to distinguish between humans and automated programs.

The term CAPTCHA (for Completely Automated Public Turing Test To Tell Computers and Humans Apart) was coined in 2000 by Luis von Ahn, Manuel Blum, Nicholas Hopper and John Langford of Carnegie Mellon University. At the time, they developed the first CAPTCHA to be used by Yahoo.

To know more details, visit - the official Captcha site or

Meet Rashmi Sinha - Founder - Slide Share - One of the most influential women in Web2.0

What she's done: The CEO and co-founder of SlideShare, Sinha was the first to create a site that allowed slides to be taken beyond limited office or educational use and shared online.

"As with video, where early entrepreneurs recognized that asynchronous sharing on the web could work, we realized with presentations that it was time to move beyond in-person presentations and that you could share slides on the web. Others could comment, favorite, download and build on this," she explains.

What to learn from her: If you're tech-oriented, and particularly if you're female, Web 2.0 is the best place to start out.

"There are more entry points in the Web 2.0 world than in more hardcore tech companies like Intel. Web 2.0 is also the right mix of the social and the technical so that women can prosper. They are contributing in a more visible manner than in other tech fields.

SlideShare is REALLY USEFUL. You can use it to:

  • view & download presentations on virtually any topic under the sun
  • upload your own presentations (ppt, pdf, odp, pps formats) and share with a global audience
  • embed presentations into blogs, websites, wikis etc
  • create an audio presentation using free slidecasting tool
  • use event functionality to send conference invites, archive slide decks, publicise your event etc
  • use the privacy feature to share presentations privately with business clients, colleagues, family members
  • participate or vote in the annual 'World's Best Presentations Contest'
Millions of people use SlideShare every day to make personal/professional contacts, generate business leads, archive conference slides, distribute academic lessons/assigments, share personal photos, conduct remote online meeting (using Skype, GTalk, Yahoo Messenger) etc.

Visit to know more about SlideShare and Rashmi Sinha.