Bootstrap Images
In Bootstrap, there are 4 image classes: .img-rounded, .img-circle, .img-thumbnail, .img-responsive.
Example 1: Create Rounded Image using ".img-rounded" class
Example 2: Create Circular Image using ".img-circle" class
Example 3: Create Thumbnail Image using ".img-thumbnail" class
Responsive Images: You can create image as responsive which will automatically adjust according to the screen size. Responsive image class is ".img-responsive" which is added to img tag.
<img class="img-responsive" src="Tiger.jpg" alt="Tiger">
The default styling for .img-responsive class applied to .img-responsive is display: block; max-width: 100%; and height: auto; to the image.
Image Gallery
You can also use Bootstrap's grid system alone with the .thumbnail class to create an image gallery.
Responsive Video
You can also create Responsive video by adding an ".embed-responsive-item" class to an <iframe>, <embed>, <video>, and <object> elements.
<div class="embed-responsive embed-responsive-16by9">
<video id="img1" controls class="embed-responsive-item">
<source src="Diving.mp4" type="video/mp4" />
</video>
</div>
Example 5: Responsive Video (Full-Screen)