In terms of technical publications, Morgan Kaufman, Prentice Hall and Addison Wesley are far more superior. But O'Reilly has Tim's personal brand behind it, and

In terms of technical publications, Morgan Kaufman, Prentice Hall and Addison Wesley are far more superior. But O'Reilly has Tim's personal brand behind it, and he has proven himself to be a visionary by betting on Unix early, then noticing the Free Software movement and fully embracing it. Then going on to godfather two editions of the web (bubble.) Think of O'Reilly as the "Virgin" airlines of Richard Branson, compared to the classics, like British Airways or Lufthansa. Yes, I too double check the spelling often.