Local storage API is another way of storing the user data in browser.
It is better than cookies in many features. local storage can save up to 5mb user data and it can be extended. if we want to create a offline application, local storage feature is the excellent.
I have seen nice books to start programming for local storage. one is html5 web application and instant local storage from packtpub.
local storage is useful for developing offline application and also to improve the browsing speed.
References
http://html5doctor.com/storing-data-the-simple-html5-way-and-a-few-tricks-you-might-not-have-known/
http://www.drdobbs.com/web-development/the-localstorage-api/240000682
