In most programming languages, including C, C++, Java, and JavaScript, the switch statement is used for control flow based on the value of a variable or expression. Here are the common rules and characteristics of a switch statement:

1. Syntax: The basic syntax of a switch statement typically includes the keyword “switch” followed by a variable or expression in parentheses, and a series of “case” statements and a “default” statement enclosed in braces.
2. Expression: The expression or variable used in the switch statement must evaluate to an integral type or an enumeration type. It cannot be a floating-point number, a string, or a boolean value.
3. Case statements: The case statements specify the different values or conditions that are being checked. Each case is defined using the keyword “case” followed by a constant value or an expression. It is then followed by a colon.
4. Execution flow: When the switch statement is encountered, the expression is evaluated. The program then searches for a case whose value matches the evaluated expression. If a match is found, the code within that case block is executed. After executing the code within a case, the program “falls through” to the subsequent cases unless a “break” statement is encountered.
5. Break statement: The “break” statement is used to terminate the execution of a switch statement. When a break statement is encountered within a case block, the program jumps to the end of the switch statement, bypassing any subsequent cases. This prevents the program from executing the code in the subsequent cases.
6. Default statement: The “default” statement is optional and is used when none of the case values match the evaluated expression. It serves as a catch-all case. If no matching case is found, the code within the default block is executed. It is usually placed at the end of the switch statement.
7. Fall-through: By default, after executing a case block, the program falls through to the subsequent cases. This means that if a break statement is not encountered, the execution will continue to the next case. This behavior allows multiple cases to execute the same code block.
8. No overlapping cases: Overlapping cases are not allowed within a switch statement. Each case value must be unique; otherwise, it will result in a compilation error.

It’s important to note that the exact rules and syntax of a switch statement can vary slightly depending on the programming language being used.