How Google Works: A Visual, Interactive Explanation
This interactive road map takes you through the anatomy of a search, from the moment you type in your query to the results page and additionally covers some of Google’s milestones such as the creation of Gmail in 2004 and Street View in 2007. Each step in the process is broken down and explained visually – a pretty remarkable process considering search results pages are displayed almost instantaneously (total time: 0.25 seconds).
Back to that spelling question…
Once Inside a Google Cluster (step 4) , your query goes through a Spelling Server. “Google doesn’t read words; it looks for patterns of characters, be they in English or Sanskrit. If it sees your requested pattern a thousand times but finds a million hits for a similar patter that’s off by one character, it connects the dots.”
It then suggest what it ‘thinks’ you meant, while providing you the results, if any, of your original search.