non-hacker users tended to work during the day. Hackers often therefore worked late into the evening or night, when the other computer users weren't competing for cycles. It's more fun, after all, to use the computer when it's responding at split-second speeds.

Now that personal computers and individual workstations are ubiquitous, there is less need to avoid day shifts. Many hackers, however, still find a 10 P.M.-to-6 A.M. or noon-to-8 A.M. schedule more pleasant than rising at the crack of dawn. There are different theories about why this is so: my personal one is that there is some correlation between the hackish sort of creativity and 'night person' physiology. It has also been suggested that working at night is an adaptation to the hacker's need for long stretches of hack mode, a literally altered state of consciousness that doesn't tolerate distractions well; I find this eminently reasonable. Just as the VCR has allowed television watchers to 'time-shift' movies, electronic mail allows the hacker to time-shift most of his communication with others, making it much less important for everyone to have exactly the same work hours.

The earliest of the hacker cultures that directly contributed to this book was the one that grew up around the PDP-1 at MIT in the early 1960s (many of these people were also in TMRC, the Tech Model Railroad Club). Later, the PDP-1 hackers formed the nucleus of the famed MIT Al Lab. Thus, when I began hacking there I connected with a tradition that was already well established, and was to continue as one of its most important sub-communities for another decade.

But MIT had no monopoly on hackers. In the 1960s and 1970s hackers congregated around any computer center that made computer time available for play. (Some of this play turned out to be very important work, but hacking is done mostly for fun, for its own sake, for the pure joy of it.) Because universities tend to be more flexible than corporations in this regard, most hackers' dens arose in university laboratories. While some of these hackers were unauthorized 'random people' like me, many hackers were paid employees who chose to stay after hours and work on their own projects or even continue their usual work purely for pleasure.

The hacker community became larger and more closely knit after 1969, when the government funded a project to see whether it would be useful and practical to let the computers at dozens of universities and other sites 'talk' to each other. The project succeeded and produced the famous ARPANET, a network that now links hundreds of computers across the country. Through the ARPANET researchers could share programs, trade research results, and send electronic mail both to individuals and to massive mailing lists. And it first allowed once-isolated hackers to talk to each other