The throws keyword in Java is used to declare that a method can throw an exception. This means that the method does not handle the exception itself, but instead passes it on to the caller of the method. The caller of the method is then responsible for handling the exception or propagating it further.

The throws keyword is used in the method signature, after the method name and parameter list. The throws keyword is followed by a comma-separated list of the exceptions that the method can throw.

For example, the following method declaration declares that the method can throw a IOException exception:

public void readFile(String fileName) throws IOException {
  // ...
}

If the readFile() method encounters an IOException while reading the file, it will throw the exception. The caller of the readFile() method will then need to handle the exception or propagate it further.

The throws keyword is not required for unchecked exceptions. Unchecked exceptions are not checked at compile time, so the compiler does not require the method to handle or specify them. However, it is still good practice to use the throws keyword for unchecked exceptions, as it makes the code more readable and maintainable.

Here are some examples of when the throws keyword might be used:

• A method that opens a file might throw a FileNotFoundException exception if the file does not exist.
• A method that reads data from a network connection might throw a IOException exception if the connection is lost.
• A method that parses a string might throw a ParseException exception if the string is not well-formed.