The Icons tool in the Visual Toolbox provide search access to a library of over a million icons from a company called Flaticon. 

The intent is to give you visual content for your email campaigns. The style of these varies, but as the name would suggest, they tend to be flat, not sort of pseudo dimensional or something like that. They look quite pleasant in email. 

You have the option of resizing. And I believe the max size of the flat icons is up to something like 512 by 512. So you can actually get quite a big visual out of this. GIFs are cached and delivered from Giphy's global backend to your email recipients. 

The useful thing about that is visuals are processed first and fastest by human beings. So if you want to really change how people are engaging your email content start by looking at the visual content rather than making it an afterthought or a decoration or something like that. And, and an icon — as we found in the world of computers — can convey a whole lot of stuff more quickly and compactly than words. 

So that's the icons tool for the Visual Toolbox.