Element and CSS class to highlight the required field in SharePoint form
![SharePoint 2016 Logo](https://markimarta.com/wp-content/uploads/2016/08/SharePoint-Logo_w492_h3121-150x150.jpg)
The red star in SharePoint form for required fields can be written as <span> control with class "ms-formvalidation":
<span class="ms-formvalidation"> *</span>
<span class="ms-formvalidation"> *</span>