You might already know, that on one specific forum or other discussion page, the user is allowed to have an image to identify them on-the-spot, this image being called an “Avatar”. But what you might not know, is that there exists a system of Avatars by which we can have one, across multiple forums and sites. This system is named “Gravatar”, and if you like, you may go to this site, which isn’t hosted by me, to sign up for your own Gravatar, if you haven’t done so already:
On my own Blog site, anybody is allowed to comment on the articles in general. The requirements are that you must leave your name and email address, and that I must approve you once. This might sound like a bit much, but it’s the only way my software can filter out spam. Two days after having set up this site, I already have 23 spams, and no real feedback.
(Edit 1/4/2016 : ) One does not need to log in, before leaving a comment on My blog.
I could have chosen to put a randomly-generated avatar for each person who comments. But instead, I’ve set WordPress.org to show any ‘Gravatar’ you might already have applied for (i.e., elsewhere). Otherwise, your comment will default to a specific avatar.