Answers for "html date value format"

html format date

<input type="date" name="begin" 
    placeholder="dd-mm-yyyy" value=""
    min="1997-01-01" max="2030-12-31">

html datetime format

<time datetime="1914">  <!-- means the year 1914 -->
<time datetime="1914-12">  <!-- means December 1914 -->
<time datetime="1914-12-20">  <!-- means 20 December 1914 -->
<time datetime="12-20">  <!-- means 20 December any year -->
<time datetime="1914-W15">  <!-- means week 15 of year 1914 -->