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The symbol table is a data structure used by compilers and interpreters to store variables as entries in the table. Each entry consists of a key (the variable's name) and an associated value (the value) The shell adds each variable (and its value) to the symbol table on startup. We can edit, remove, or export shell variables at will, using the proper builtin utilities (which we'll talk about later on in this series) All shells have some sort of symbol table implementation, although some shells might have different names for it.