For all the trouble we have to take to protect, backup, and maintain our data, when we want to get rid of it, it turns out to be remarkably difficult. Do we delete Overwriting delete? Overwrite 40 times? Overwrite 40 times including all the slack space? Degauss? Get out the thermite?
This site presents a faster and easier option. There is software, and also a paper (possibly self-serving ...) explaining the option, and why it is very often good enough.