Interpretation
An interpreter is a program that reads instructions one at a time, decodes what they mean, then executes them.
Many parts of programs are actually interpreters:
pow(x, 3)
printf("i = %5d\n", i)
Rule of thumb: Each level of interpretation of a program costs an order of magnitude in performance.
Eliminating interpretation (increasing the degree of binding between a program and the particular application) is an important optimization.
Goal: Combine elegant, high-level expression of a program with efficient execution.