Form controls have some default styling without using any special classes.
However labels and controls can be wrapped in .form-group
tags for optimum spacing.
<form>
<div class="form-group">
<label for="input-email">Email address</label>
<input type="email" class="form-control" id="input-email" placeholder="Email">
</div>
<div class="form-group">
<label for="input-password">Password</label>
<input type="password" class="form-control" id="input-password" placeholder="Password">
</div>
<button type="submit" class="btn btn-default">Submit</button>
</form>