Finding the locators using selenium

Direct Reference  Using one of the direct references to the HTML element

Id=MyButton (note in this case, “Id =” is not even required)

Name=Description_Field

Value=ABC XYZ

Link=Contact Us

XPath, (XML Path Language)  :xpath, for locators starting with "//"
Reference: http://www.w3schools.com/xpath/default.asp Relatively straightforward to compose and read later down the track.
xpath=//img[@alt='The image alt text']
xpath=//table[@id='table1']//tr[4]/td[2]
xpath=//a[contains(@href,'#id1')]
xpath=//a[contains(@href,'#id1')]/@class
xpath=(//table[@class='stylee'])//th[text()='theHeaderText']/../td
xpath=//input[@name='name2' and @value='yes']
xpath=//*[text()="right"]
/html/body/div[1]/div[5]/div/table/tbody/tr/td/p/a[3] (An example bad XPath – it will break as soon as the page layout changes a bit)


DOM and CSS : 
dom=document.images[0] (the first image in the page)
css=H1.topic (the first heading with the class name of topic) or css=h1.topic[value="Topic Index"] (the heading with the specific text)
dom=document.forms['myForm'].myDropdown
dom=document.images[56]
dom=function foo() { return document.links[1]; }; foo();
css=a[href="#id3"]
css=span#firstChild + span

Keyboard and Coordinates
You can also go to the extreme of KeyDown and KeyUp