A few weeks ago, I noticed that Google shows facts next to some Wikipedia results. This feature is called Structured Snippets and it's not limited to Wikipedia results.
"Structured Snippets is a new feature that incorporates facts into individual result snippets in Web Search. As seen in the example below, interesting and relevant information is extracted from a page and displayed as part of the snippet for the query [nikon d7100]," informs Google.
"Structured Snippets is the latest collaboration between Google Research and the Web Search team employing that data to seamlessly provide the most relevant information to the user. We use machine learning techniques to distinguish data tables on the Web from uninteresting tables, e.g., tables used for formatting web pages. We also have additional algorithms to determine quality and relevance that we use to display up to four highly ranked facts from those data tables," mentions the Google Research blog.
You don't need special formatting: Google extracts information from existing tables. It's interesting to notice that Google has always used tables from web pages to extract useful data. Google Sets, one of the earliest Google Labs services, used lists and tables from web pages to generate lists of related terms. Google also built a search engine for tables and shows data from tables in cards and snippets.
