1. Vertical form

                      <form action="/action_page.php">

                      </form>
                 

A form should have action

2. with fields

                 <form action="/action_page.php">
                        <div class="form-group">
                          <label for="email">Email address:</label>
                          <input type="email" class="form-control" id="email">
                        </div>
                        <div class="form-group">
                          <label for="pwd">Password:</label>
                          <input type="password" class="form-control" id="pwd">
                        </div>
                        <div class="checkbox">
                          <label><input type="checkbox"> Remember me</label>
                        </div>
                        <button type="submit" class="btn btn-default">Submit</button>
                      </form>

                

2. Inline Form

                <form class="form-inline" action="/action_page.php">
                    <div class="form-group">
                      <label for="email">Email address:</label>
                      <input type="email" class="form-control" id="email">
                    </div>
                    <div class="form-group">
                      <label for="pwd">Password:</label>
                      <input type="password" class="form-control" id="pwd">
                    </div>
                    <div class="checkbox">
                      <label><input type="checkbox"> Remember me</label>
                    </div>
                    <button type="submit" class="btn btn-default">Submit</button>
                  </form>

                  

3. Horizontal Form

                  <form class="form-horizontal" action="/action_page.php">
                      <div class="form-group">
                        <label class="control-label col-sm-2" for="email">Email:</label>
                        <div class="col-sm-10">
                          <input type="email" class="form-control" id="email" placeholder="Enter email">
                        </div>
                      </div>
                      <div class="form-group">
                        <label class="control-label col-sm-2" for="pwd">Password:</label>
                        <div class="col-sm-10">
                          <input type="password" class="form-control" id="pwd" placeholder="Enter password">
                        </div>
                      </div>
                      <div class="form-group">
                        <div class="col-sm-offset-2 col-sm-10">
                          <div class="checkbox">
                            <label><input type="checkbox"> Remember me</label>
                          </div>
                        </div>
                      </div>
                      <div class="form-group">
                        <div class="col-sm-offset-2 col-sm-10">
                          <button type="submit" class="btn btn-default">Submit</button>
                        </div>
                      </div>
                    </form>