image classes bootstrap code example

Example 1: bootstrap Image thumbnails

In addition to our border-radius utilities, you can use 
.img-thumbnail to give an image a rounded 1px border appearance.

<img src="..." alt="..." class="img-thumbnail">

Example 2: img-fluid bootstrap

<img class="img-fluid" src="" alt=""> //This will make your image responsive

Example 3: bootstrap img src

<img src="..." class="rounded mx-auto d-block" alt="...">