Sidewiki allows people to share travel plans or opinions of experiences. "When researching advice on heart disease prevention or looking for museums to visit in New York City, many others have done the same and could have added their knowledge along the way," writes Sundar Pichai, vice president of product management, and Michal Cierniak, engineering lead for Google Sidewiki, in a blog post.

Sidewiki joins several startups like Kutano that over the years have launched at venture capital trade shows, such as DEMO. The tools also will post notes across multiple sites that have the same content, providing a social aspect to sharing information.

For example, a note about a quote from President Barack Obama would appear on all Web pages that include the same quote. Google also brings in relevant posts from blogs and other sources that talk about the current page so people can discover their insights more easily, right next to the page they refer to, according to Pichai and Cierniak.

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