When we talk to people about passwords, especially about websitepasswords , generally what we teach themis some variant of 'do not write down your passwords and always usedifferent ones on each service'. Time after time, what happens is thatpeople follow half of this; they have only one common password, but theydon't write it down.

It has recently occurred to me that there is a sensible explanationfor this result (beyond the obvious one that it is the more convenientoption if you are only

Every so often, people compare programming to something like buildinga house and ask why software projects can't be half as well estimatedas physical engineering projects typically are. One of the many reasonsthat this is a bad comparison is that physical engineering is differentfrom software engineering in a crucial respect.

The process of getting something physical constructed is generallydivided into two phases: design, the intellectual engineering work, andconstruction, which is theoretically mere unintelligent physical labour.Thus, once you've finished the design work