#18: JIT - Just-in-time compilation
Source code can then be executed in two ways. Language implementations in general either interpret or compile it. In order to run an interpreted program, you need one extra binary: an interpreter. Interpretation is simple: you read source code line by line and execute it. The compilation is much harder. A special program called a compiler reads your source code ahead of time (AOT) and translates it into machine code. After this translation your program is standalone. You don't need a compiler to run it. Only you and your CPU.
Turns out this distinction is not that clear at all these days. Almost every language implementation performs compilation behind the scenes. And many languages that have a compiler produce code that needs an interpreter anyway. What?
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