Understanding what bytecode is

Bytecode is a sequence of machine instructions encoded in a binary format and written not for a CPU to execute, but instead for an abstract (or virtual) machine instruction set that embodies the semantics of a given programming language. Although many bytecode instruction sets for languages such as Java use a byte as the smallest instruction size, almost all of them include longer instructions. Such longer instructions have one or more operands. Since many kinds of operands must be aligned at a word boundary with an address that is a multiple of four or eight, a better name for many forms of bytecode might be wordcode. The term bytecode is commonly used for such abstract machines, regardless of the instruction’s size.

The languages that are directly responsible for popularizing bytecode are Pascal and SmallTalk. These languages adopted bytecode for different reasons that remain important considerations for programming languages that are defined...