John Wait: Many popular newer programming languages trace their roots to C. Unix has had direct and indirect influence on many newer operating systems. To what do you attribute the longevity and popularity of both C and Unix?
Brian Kernighan: Both C and Unix strike a very good balance among expressiveness, efficiency and economy of means. That means that they are a good base to build on: the good ideas are worth stealing and the efficiency sets a standard of comparison. It’s also easier for people to make a transition from something familiar than to make a big change, so a language or system that has significant elements of familiarity is more likely to be a success.