Difference between Placeholder and Value

While using input tag in HTML form we use two common attributes that are value and placeholder.

If as seen from user perspective these two seems to be same , because while entering the data these two attributes are actually the content which are already written in form before user.

e.g. :-

<input type="text" value="Alok"/>

<input type="text" placeholder="Alok"/>

The value attribute define the default value of input. If user does not give any input then this default value would be considered as input while the placeholder is just the dummy text which shows or depicts that what type of text is to be input in the field.If for any input tag value attribute is not defied and only placeholder is defied then if user is not giving any input will be considered as blank.