This paper presents a comparative study of spelling errors that are corrected as you type, vs. those that remain uncorrected. First, we generate naturally occurring online error correction data by logging users’ keystrokes, and by automatically deriving pre- and postcorrection strings from them. We then perform an analysis of this data against the errors that remain in the final text as well as across languages. Our analysis shows a clear distinction between the types of errors that are generated and those that remain uncorrected, as well as across languages.