<div class="modal" tabindex="-1" role="dialog">
  <div class="modal-dialog" role="document">
    <div class="modal-content">
      <div class="modal-header">
        <h5 class="modal-title">عنوان مودال</h5>
        <button type="button" class="close" data-dismiss="modal" aria-label="Close">
          <span aria-hidden="true">×</span>
        </button>
      </div>
      <div class="modal-body">
        <p>محتوای مودال در این قسمت قرار میگیرد.</p>
      </div>
      <div class="modal-footer">
        <button type="button" class="btn btn-secondary" data-dismiss="modal">بستن</button>
        <button type="button" class="btn btn-primary">اعمال تغییرات</button>
      </div>
    </div>
  </div>
</div>
دمو
<button type="button" class="btn btn-primary mr-2 mb-2" data-toggle="modal" data-target="#exampleModal">
  اجرای مودال
</button>

<div class="modal" tabindex="-1" role="dialog" id="exampleModal">
  <div class="modal-dialog" role="document">
    <div class="modal-content">
      <div class="modal-header">
        <h5 class="modal-title">عنوان مودال</h5>
        <button type="button" class="close" data-dismiss="modal" aria-label="Close">
          <span aria-hidden="true">×</span>
        </button>
      </div>
      <div class="modal-body">
        <p>محتوای مودال در این قسمت قرار میگیرد.</p>
      </div>
      <div class="modal-footer">
        <button type="button" class="btn btn-secondary" data-dismiss="modal">بستن</button>
        <button type="button" class="btn btn-primary">اعمال تغییرات</button>
      </div>
    </div>
  </div>
</div>
همراه اسکرول
<div class="modal" tabindex="-1" role="dialog">
  <div class="modal-dialog" role="document">
    <div class="modal-content">
      <div class="modal-header">
        <h5 class="modal-title">عنوان مودال</h5>
        <button type="button" class="close" data-dismiss="modal" aria-label="Close">
          <span aria-hidden="true">×</span>
        </button>
      </div>
      <div class="modal-body">
        ...
      </div>
      <div class="modal-footer">
        <button type="button" class="btn btn-secondary" data-dismiss="modal">بستن</button>
        <button type="button" class="btn btn-primary">اعمال تغییرات</button>
      </div>
    </div>
  </div>
</div>
قرارگیری از وسط
<div class="modal fade" id="exampleModalCenter" tabindex="-1" role="dialog" aria-hidden="true">
  <div class="modal-dialog modal-dialog-centered" role="document">
    <div class="modal-content">
      <div class="modal-header">
        <h5 class="modal-title" id="exampleModalCenterTitle">عنوان مودال</h5>
        <button type="button" class="close" data-dismiss="modal" aria-label="Close">
          <i class="ti-close"></i>
        </button>
      </div>
      <div class="modal-body">
        ...
      </div>
      <div class="modal-footer">
        <button type="button" class="btn btn-secondary" data-dismiss="modal">بستن
        </button>
        <button type="button" class="btn btn-primary">اعمال تغییرات</button>
      </div>
    </div>
  </div>
</div>
سایزها
<!-- .modal-xl -->
<div class="modal fade" tabindex="-1" role="dialog" aria-hidden="true">
  <div class="modal-dialog modal-xl">
    <div class="modal-content">
      <div class="modal-header">
        <h6 class="modal-title">مودال خیلی بزرگ</h6>
        <button type="button" class="close" data-dismiss="modal" aria-label="Close">
          <i class="ti-close"></i>
        </button>
      </div>
      <div class="modal-body">
        ...
      </div>
      <div class="modal-footer">
        <button type="button" class="btn btn-secondary" data-dismiss="modal">بستن
        </button>
        <button type="button" class="btn btn-primary">اعمال تغییرات</button>
      </div>
    </div>
  </div>
</div>

<!-- .modal-lg -->
<div class="modal fade" tabindex="-1" role="dialog" aria-hidden="true">
  <div class="modal-dialog modal-lg">
    <div class="modal-content">
      <div class="modal-header">
        <h6 class="modal-title">مودال بزرگ</h6>
        <button type="button" class="close" data-dismiss="modal" aria-label="Close">
          <i class="ti-close"></i>
        </button>
      </div>
      <div class="modal-body">
        ...
      </div>
      <div class="modal-footer">
        <button type="button" class="btn btn-secondary" data-dismiss="modal">بستن
        </button>
        <button type="button" class="btn btn-primary">اعمال تغییرات</button>
      </div>
    </div>
  </div>
</div>

<!-- .modal-sm -->
<div class="modal fade" tabindex="-1" role="dialog" aria-hidden="true">
  <div class="modal-dialog modal-sm">
    <div class="modal-content">
      <div class="modal-header">
        <h6 class="modal-title">مودال کوچک</h6>
        <button type="button" class="close" data-dismiss="modal" aria-label="Close">
          <i class="ti-close"></i>
        </button>
      </div>
      <div class="modal-body">
        ...
      </div>
      <div class="modal-footer">
        <button type="button" class="btn btn-secondary" data-dismiss="modal">بستن
        </button>
        <button type="button" class="btn btn-primary">اعمال تغییرات</button>
      </div>
    </div>
  </div>
</div>
مودال متفاوت
<button type="button" class="btn btn-primary" data-toggle="modal" data-target="#exampleModal" data-whatever="@mdo">
  مودال برای @mdo
</button>

<button type="button" class="btn btn-primary" data-toggle="modal" data-target="#exampleModal" data-whatever="@fat">
  مودال برای  @fat
</button>

<button type="button" class="btn btn-primary" data-toggle="modal" data-target="#exampleModal" data-whatever="@getbootstrap">مودال برای 
  @getbootstrap
</button>

<!-- modal -->
<div class="modal fade" id="exampleModal" tabindex="-1" role="dialog" aria-hidden="true">
  <div class="modal-dialog" role="document">
    <div class="modal-content">
      <div class="modal-header">
        <h5 class="modal-title" id="exampleModalLabel">پیام جدید</h5>
        <button type="button" class="close" data-dismiss="modal" aria-label="Close">
          <i class="ti-close"></i>
        </button>
      </div>
      <div class="modal-body">
        <form>
          <div class="form-group">
            <label for="recipient-name" class="col-form-label">دریافت کنندگان</label>
            <input type="text" class="form-control" id="recipient-name">
          </div>
          <div class="form-group">
              <label for="message-text" class="col-form-label">پیام:</label>
              <textarea class="form-control" id="message-text"></textarea>
            </div>
         </form>
       </div>
       <div class="modal-footer">
          <button type="button" class="btn btn-secondary" data-dismiss="modal">بستن
          </button>
          <button type="button" class="btn btn-primary">ارسال</button>
       </div>
     </div>
  </div>
</div>