This is pretty useful in giving a visual indication to the user when a form field is required.
The CSS:
.form-group.required .control-label:after { content:"*"; color:red; }
Then in your HTML:
<form> <div class="form-group required"> <label class="control-label">Required Field</label> ... </div> </form>
There will now be a nice little “*” after the label for “Required Field”.