Difference between ng-model and data-ng-model

Question

I am new with the AngularJs. Can anyone say the difference between ng-model and data-ng-model?

With ng-model

First Name  :  <input type="text" ng-model="fname" id="fname">
Second Name :  <input type="text" ng-model="lname" id="lname">  

With data-ng-model

First Name  :  <input type="text" data-ng-model="fname" id="fname">
Second Name :  <input type="text" data-ng-model="lname" id="lname">  

Answer 1

while both ng-model and data-ng-model would work, HTML5 expects any custom attribute to be prefixed by data-.

<!-- not HTML5 valid --> <input type="text" ng-model="name">  <!-- HTML5 valid --> <input type="text" data-ng-model="name"> 

Answer 2

They are the same. Angular strips the data- part from the attribute. From the docs:

Angular normalizes an element's tag and attribute name to determine which elements match which directives... The normalization process is as follows:

1. Strip x- and data- from the front of the element/attributes.
2. Convert the :, -, or _-delimited name to camelCase.