netlify.html

<form action="/thanks.html" name="Bolaji's form" method="POST" data-netlify="true">
   <div class="form-group">
      <label>Name:</label>
      <input type="text" class="form-control" id="name" placeholder="Name">
      <div class="invalid-feedback">
         Name must be between 2 and 20 characters
      </div>
   </div>
   <div class="form-group">
      <label>Email:</label>
      <input type="text" class="form-control" id="email" placeholder="Email address">
      <div class="invalid-feedback">
         Enter a valid email address
      </div>
   </div>
   <div class="form-group">
      <label>Telephone:</label>
      <input type="text" class="form-control" id="phone" placeholder="Phone number">
      <div class="invalid-feedback">
         Enter a valid number
      </div>
   </div>
   <input type="submit" value="Send" class="btn btn-info btn-block">
</form>