On June 14, 2014. Google announced officially that this feature is live to everyone for international targeting section of “Search Traffic”
There are 3 different ways of creating international sites that are seen as best SEO practices:
1) Using a sub directory for your sub domains – http://www.abc.com/ca
2) Top level domain – http://www.abc.ca
3) Sub domain – http://ca.abc.com
The hreflang is implemented to any of the above domains. Hreflang tag helps to tell google which version of the website should be shown in which country.
Below is the code should add in a pages tag of any multi lingual website like abc.com
Note: X-default is for alternative version of the page means if site is opening in italy and website is not in italy then set to default means home page or the page owner want.
For more details visit here: http://www.seroundtable.com/google-international-targeting-webmaster-tools-18842.html