Forms

This samples were taken from Bootstrap docs and are here added as example

<form>
            <div class="form-group">
                <label for="exampleInputEmail1">Email address</label>
                <input type="email" class="form-control" id="exampleInputEmail1" aria-describedby="emailHelp"
                       placeholder="Enter email">
                <small id="emailHelp" class="form-text text-muted">We'll never share your email with anyone
                    else.</small>
            </div>
            <div class="form-group">
                <label for="exampleInputPassword1">Password</label>
                <input type="password" class="form-control" id="exampleInputPassword1" placeholder="Password">
            </div>
            <div class="form-check">
                <input type="checkbox" class="form-check-input" id="exampleCheck1">
                <label class="form-check-label" for="exampleCheck1">Check me out</label>
            </div>
            <button type="submit" class="btn btn-primary">Submit</button>
        </form>

<form>
            <div class="form-group">
                <label for="exampleFormControlInput1">Email address</label>
                <input type="email" class="form-control" id="exampleFormControlInput1" placeholder="name@example.com">
            </div>
            <div class="form-group">
                <label for="exampleFormControlSelect1">Example select</label>
                <select class="form-control" id="exampleFormControlSelect1">
                    <option>1</option>
                    <option>2</option>
                    <option>3</option>
                    <option>4</option>
                    <option>5</option>
                </select>
            </div>
            <div class="form-group">
                <label for="exampleFormControlSelect2">Example multiple select</label>
                <select multiple class="form-control" id="exampleFormControlSelect2">
                    <option>1</option>
                    <option>2</option>
                    <option>3</option>
                    <option>4</option>
                    <option>5</option>
                </select>
            </div>
            <div class="form-group">
                <label for="exampleFormControlTextarea1">Example textarea</label>
                <textarea class="form-control" id="exampleFormControlTextarea1" rows="3"></textarea>
            </div>
        </form>

<form>
            <div class="form-row">
                <div class="form-group col-md-6">
                    <label for="inputEmail4">Email</label>
                    <input type="email" class="form-control" id="inputEmail4" placeholder="Email">
                </div>
                <div class="form-group col-md-6">
                    <label for="inputPassword4">Password</label>
                    <input type="password" class="form-control" id="inputPassword4" placeholder="Password">
                </div>
            </div>
            <div class="form-group">
                <label for="inputAddress">Address</label>
                <input type="text" class="form-control" id="inputAddress" placeholder="1234 Main St">
            </div>
            <div class="form-group">
                <label for="inputAddress2">Address 2</label>
                <input type="text" class="form-control" id="inputAddress2" placeholder="Apartment, studio, or floor">
            </div>
            <div class="form-row">
                <div class="form-group col-md-6">
                    <label for="inputCity">City</label>
                    <input type="text" class="form-control" id="inputCity">
                </div>
                <div class="form-group col-md-4">
                    <label for="inputState">State</label>
                    <select id="inputState" class="form-control">
                        <option selected>Choose...</option>
                        <option>...</option>
                    </select>
                </div>
                <div class="form-group col-md-2">
                    <label for="inputZip">Zip</label>
                    <input type="text" class="form-control" id="inputZip">
                </div>
            </div>
            <div class="form-group">
                <div class="form-check">
                    <input class="form-check-input" type="checkbox" id="gridCheck">
                    <label class="form-check-label" for="gridCheck">
                        Check me out
                    </label>
                </div>
            </div>
            <button type="submit" class="btn btn-primary">Sign in</button>
        </form>

Read more and know more from Bootstrap forms here.