There are few options on how to include/import Swiper into your project:
We can install Swiper from NPM
  $ npm install swiper@6
  // import Swiper JS
  import Swiper from 'swiper';
  // import Swiper styles
  import 'swiper/swiper-bundle.css';
  const swiper = new Swiper(...);
By default Swiper exports only core version without additional modules (like Navigation, Pagination, etc.). So you need to import and configure them too:
  // core version + navigation, pagination modules:
  import SwiperCore, { Navigation, Pagination } from 'swiper/core';
  // configure Swiper to use modules
  SwiperCore.use([Navigation, Pagination]);
  // init Swiper:
  const swiper = new Swiper(...);
If you want to import Swiper with all modules (bundle) then it should be imported from swiper/bundle:
  // import Swiper bundle with all modules installed
  import Swiper from 'swiper/bundle';
  // init Swiper:
  const swiper = new Swiper(...);
If you don't want to include Swiper files in your project, you may use it from CDN. The following files are available:
<link rel="stylesheet" href="https://unpkg.com/swiper/swiper-bundle.css" />
<link rel="stylesheet" href="https://unpkg.com/swiper/swiper-bundle.min.css" />
<script src="https://unpkg.com/swiper/swiper-bundle.js"></script>
<script src="https://unpkg.com/swiper/swiper-bundle.min.js"></script>
If you use ES modules in browser, there is a CDN version for that too:
<script type="module">
  import Swiper from 'https://unpkg.com/swiper/swiper-bundle.esm.browser.min.js'
  const swiper = new Swiper(...)
</script>
If you want to use Swiper assets locally, you can directly download them from https://unpkg.com/swiper/
Now, we need to add basic Swiper layout to our app:
<!-- Slider main container -->
<div class="swiper-container">
  <!-- Additional required wrapper -->
  <div class="swiper-wrapper">
    <!-- Slides -->
    <div class="swiper-slide">Slide 1</div>
    <div class="swiper-slide">Slide 2</div>
    <div class="swiper-slide">Slide 3</div>
    ...
  </div>
  <!-- If we need pagination -->
  <div class="swiper-pagination"></div>
  <!-- If we need navigation buttons -->
  <div class="swiper-button-prev"></div>
  <div class="swiper-button-next"></div>
  <!-- If we need scrollbar -->
  <div class="swiper-scrollbar"></div>
</div>
In addition to Swiper's CSS styles, we may need to add some custom styles to set Swiper size:
.swiper-container {
  width: 600px;
  height: 300px;
}
Finally, we need to initialize Swiper in JS:
const swiper = new Swiper('.swiper-container', {
  // Optional parameters
  direction: 'vertical',
  loop: true,
  // If we need pagination
  pagination: {
    el: '.swiper-pagination',
  },
  // Navigation arrows
  navigation: {
    nextEl: '.swiper-button-next',
    prevEl: '.swiper-button-prev',
  },
  // And if we need scrollbar
  scrollbar: {
    el: '.swiper-scrollbar',
  },
});
As you see it is really easy to integrate Swiper into your website or app. So here are your next steps:
swiper tag.