The "raise" statement in Python is used to raise an exception. It allows the programmer to manually raise an exception at a specific point in the code, rather than waiting for the occurrence of an error or exception by the interpreter.

The general syntax for using "raise" is:

raise Exception("Error message")  

Here, "Exception" is the type of exception to be raised, and "Error message" is the optional error message that describes the exception. The exception can be any built-in or user-defined exception class.

For example, if you want to raise a ValueError with a custom error message, you can use the following code:

raise ValueError("Invalid input!")  

When the "raise" statement is executed, the program will immediately stop executing the current block of code and go to the nearest exception handler that can catch the raised exception. If no exception handler is found, the program terminates and displays a traceback.

The "raise" statement can also be used without an argument to re-raise the current exception that is being handled. This is useful when you want to preserve the original exception and its traceback.

Here's an example:

try:  
    raise ValueError("Something went wrong!")  
except ValueError as e:  
    print("Caught exception:", e)  
    raise  # Re-raise the exception  

In this example, the "raise" statement inside the "except" block re-raises the same ValueError that was caught, allowing it to be handled by an outer exception handler or, if there is none, causing the program to terminate.