What is CE Gravatar?
CE Gravatar is an ExpressionEngine® plugin. This means that it does not have a user interface, but is intended as a development tool to be used in your templates. It allows you, as the developer, to dynamically include Gravatar images on-the-fly in your templates.
Why CE Gravatar?
Because it provides an easy interface to all of the options currently available for Gravatar images. You can even run conditional statements to check if a Gravatar image exists for an email address. A better question is, “Why not CE Gravatar?”