Quote from Wil Shipley

A great description of what most programmers *really* have to deal with every day.

In college computer science classes, we learn all about b*trees and linked lists and sorting algorithms and a ton of crap that I honestly have never, ever used, in 25 years of professional programming. (Except hash tables. Learn those. You'll use them!)

What I do write – every day, every hour – are heuristics that try to understand and intuit what the user is telling me, without her having to learn my language.

From Pimp My Code, Part 16: On Heuristics and Human Factors. This also has a great example of the contortions one must make when dealing with real world users and real world data.