BURLINGAME, Calif.  In the span of just a couple of years, Hadoop, a free software program named after a toy elephant, has taken over some of the world’s biggest Web sites. It controls the top search engines and determines the ads displayed next to the results. It decides what people see on Yahoo’s homepage and finds long-lost friends on Facebook.

It has achieved this by making it easier and cheaper than ever to analyze and access the unprecedented volumes of data churned out by the Internet. By mapping information spread across thousands of cheap computers and by creating an easier means for writing analytical queries, engineers no longer have to solve a grand computer science challenge every time they want to dig into data. Instead, they simply ask a question.

“It’s a breakthrough,” said Mark Seager, head of advanced computing at the Lawrence Livermore National Laboratory. “I think this type of technology will solve a whole new class of problems and open new services.”

Three top engineers from Google, Yahoo and Facebook, along with a former executive from Oracle, are betting it will. They announced a start-up Monday called Cloudera, based in Burlingame, Calif., that will try to bring Hadoop’s capabilities to industries as far afield as genomics, retailing and finance.