There are two ways to insert images into the content. If we want to just display an image at the top of the content, we can use the default image field of Drupal content types.
But to add images within content, we have to install 'insert' module.
You need to install the module and enable it.
Enable insert button and configuration by going to the image field setting for the content type (e.g. blog).
After enabled, now we can insert images using below steps.