Control flow

In 1966 Corrado Böhm and Giuseppe Jacopini published a result in Communications of the ACM that sounds almost too simple: any flowchart can be rewritten using only three ways of combining steps, one after another, a choice between two branches, and a loop.

Two years later, in March 1968, the same journal printed a letter from Edsger Dijkstra arguing that the unrestricted goto made programs impossible to reason about. The editor, Niklaus Wirth, gave it the title it is remembered by, "Go To Statement Considered Harmful". Structured programming, the style every modern language teaches, grew out of those two pieces.