AltaVista, one of the leading search engines of the 1990s, has died. It was 18 years old. It had languished for years before its owner, Yahoo, finally pulled the plug.

Silicon Valley is littered with the graves of firms that tried and failed to gain traction in the search market. Today, the U.S. market is dominated by two companies: Microsoft (whose technology also powers Yahoo's search engine) and Google (whose technology also powers the AOL and Ask search engines). Internationally, Yandex and Baidu have significant market share in Russia and China, respectively.

Why does Google have so few competitors? Gabriel Weinberg is one of the few entrepreneurs who have managed to gain some traction in the search-engine market. His site, DuckDuckGo, touts industry-leading privacy features and "zero click info" boxes, which show information pulled from sites like Wikipedia and Wolfram Alpha.