A symbol table is a data structure used by a compiler or interpreter to store information about the occurrence of various entities such as objects, classes, variable names, function names, interfaces, etc. . It is used by both the analysis and synthesis parts of a compiler. The symbol table is defined as the set of Name and Value pairs, and it is an important data structure created and maintained by the compiler in order to keep track of semantics of variables. The symbol table stores information about the scope and binding information about names, information about instances of various entities such as variable and function names, classes, objects, etc. .

The symbol table is accessed by most phases of a compiler, beginning with lexical analysis, and it is used to perform various operations such as:

• Insert: This operation is used to insert a new entry into the symbol table.
• Lookup: This operation is used to search for a name in the symbol table and determine its attributes.
• Type checking: This operation is used to verify assignments and expressions in the source code are semantically correct.
• Scope resolution: This operation is used to determine the scope of a name.

The symbol table can be implemented in various ways such as a linear or hash table, and it can be either sorted or unsorted. The symbol table is used to store essential information about every symbol contained within the program, including keywords, data types, operators, functions, variables, procedures, constants, and literals.