You most likely created image styles with Drupal's "Scale and crop" image effect. This style allows you to display large images on a smaller scale and save precious screen space.
There is one issue with such styling though. Often the most interesting point of the image gets chopped off. The "Focal Point" contrib module helps avoid this issue.
In this tutorial, you will learn to use this module to select the most important portion of the image you would like to show to your readers.