A simple example of Selenium WebDriver implicit exception handling can be described as follows:

1. Define an element on a page
2. Create a method to retrieve the text from the element on the page
3. In the signature of the method, add throws Exception
4. Do not handle a specific exception like ElementNotFoundException:

// create a method to retrieve the text from an element on a page
@FindBy(id="submit")
protected M submit;

public String getText(WebElement element) throws Exception {
    return element.getText();
}

// use the method
LoginPO.getText(submit);

Now, when using an assertion method, TestNG will implicitly throw an exception if the condition is not met:

1. Define an element on a page
2. Create a method to verify the text of the element on a page
3. Cast the expected and actual text to the TestNG's assertEquals method
4. TestNG will throw an AssertionError
5. TestNG engages the difference viewer to compare the result if it fails:

// create a method to verify the text from an element on a page
@FindBy(id="submit")
protected M submit;

public void verifyText(WebElement element,
                       String expText)
                       throws AssertionError {

    assertEquals(element.getText(),
                 expText,
                 "Verify Submit Button Text");
}

// use the method
LoginPO.verifyText(submit, "Sign Inx");

// throws AssertionError
java.lang.AssertionError: Verify Text Label expected [ Sign Inx] but found [ Sign In]

Expected : Sign Inx
Actual : Sign In
<Click to see difference>