SEARCH ENGINE SMACK DOWN: When it comes to search engines, size matters - at least to Google.

After years of silence about the vastness of its Web index, Google announced Friday it had found 1 trillion unique Web pages. "We're proud to have the most comprehensive index of any search engine, and our goal always has been to index all the world's data," a Google spokeswoman said in a statement.

A bit of history: In August 2005, a similar claim put forward by Yahoo that it had indexed 20 billion URLs prompted a public rebuke from Google. "Our scientists are not seeing the increase claimed in the Yahoo index," a Google representative told blogger and search expert John Battelle.

A month later, Google asserted it had indexed 26 billion URLS and was "more than 3 times larger than any other search engine."

But if Google was hoping for a fight, it didn't find one. Yahoo didn't have an immediate comment Friday, and Microsoft declined to engage, saying in a statement that its index is "one of the largest in the industry."