Switching to frame, Windows, alert in Selenium WebDriver

1. How to Switch from one frame to another

 // How to Switch from one frame to another  
 WebElement iFrmeElement = driver.findElement(By.xpath("xPath for Frame"));  
 driver.switchTo().frame(frameElement);  
 //Or  
 driver.switchTo().frame(id or name)  
 //Or  
 driver.switchTo().frame(index of frame)  

2. We can switch to default again by:

 driver.switchTo().defaultContent();  

3. We can switch to a window based on name, Id or Windows handle

 driver.switchTo().window("windowName");  

4. We can switch to an alert

 Alert alert = driver.switchTo().alert();  
 // We can close an alert using methods for alert object  
 alert. accept();