Images

Responsive images

Placeholder Responsive image 
<img src="..." class="img-fluid" alt="Responsive image">

Image thumbnails

A generic square placeholder image with a white border around it, making it resemble a photograph taken with an old instant camera 200x200 
<img src="..." alt="..." class="img-thumbnail">

Aligning images

Placeholder 200x200 Placeholder 200x200 
<img src="..." class="rounded float-left" alt="...">
<img src="..." class="rounded float-right" alt="...">
Placeholder 200x200 
<img src="..." class="rounded mx-auto d-block" alt="...">
Placeholder 200x200 
<div class="text-center">
  <img src="..." class="rounded" alt="...">
</div>

Picture

​<picture>
  <source srcset="..." type="image/svg+xml">
  <img src="..." class="img-fluid img-thumbnail" alt="...">
</picture>