Frame is a html document inside another html document. 
• Web driver handles one page/html document at a time. 
To control another frame, we always need to switch
• Driver.switchTo.frame(webelement) à find the iframe and pass as a param 
• Driver.switchTo.frame(string) à find the id or name of the iframe 
and pass as a param 
• Driver.switchTo.frame(int) à find the index and pass as a param