Below are the few APIs with short description which has been introduced in HTML5 :
Use it as a drawing surface within the browser.
# Contacts : Allow to have local repository for contacts storage and access. rather than storing on different websites like Google+, Facebook etc.
# File API : Allow to store data on of user’s computer sandboxed area ( i.e. untrusted, unverified).
# Forms : Boosted with built-in validations.
# Geolocation : Give user location information, useful with mobility devices.
# IndexedDB : local storage within browser. To store sizable amount of structured data and indexed like other db for high performance. Object database.
# MediaCapture : Enable browser to access device native like camera, webcam so on..
# Microdata : using Metadata of data.
# Messaging :
# Offline Web Application : Mark certain pages and resources being available even there is no internet. can make resources being server-only like search and dynamic listing.
# Selection : Earlier searching-selecting a element out of Document object Model(DOM) was painful. Provide browser native selection.
# Server-Sent Events : sent message form server to browser in one direction.
# WebSockets : Provide duplex way of communication. example chat application
# Web Notification : notification to user initiated from browser.
# Web Storage : comes as Local storage(give more space than save on cookies i.e. 4kb limit for cookies unlike cookies data is not sent to server with each request) and Session storage (same as previous server side session).
# Web Workers : UI threading make page responsive can do multiple stuffs at one time.
# XMLHttpRequestLevel2 : AJAX request enhancement. Allow cross domain posting.