What is a place holder image?
An image placeholder is a dummy image designed to draw attention to the need for an actual image. Wikipedia image placeholders were meant to be used on articles, especially those of living people, for the purpose of trying to obtain a freely-licensed image for them.
How do you use Pravatar?
to use Pravatar, it is as simple as adding the URL or the Direct Image ID to your code. The ID pulls up images from Pexels. You can see a list of the images being used here. Make an adjustment in the ID to pull up a specific image.