Many projects use shields like the one below to indicate their current status, number of followers etc:
Back in 2013 these shields were very inconsistent in appearance. It turns out we have a designer to thank for standardising them into what we see today:
Basically, the badges were often neither functionally optimal nor aesthetically pleasing. I saw a missed opportunity there. So, despite my rusty design skills, I hopped into Photoshop. Some time later I emerged with a rage diamond. It was a simple Photoshop file with a badge template that I took the time to design properly: consistent padding, a more legible typeface despite a similar font size, better contrast, softer colors, a more subtle gradient, etc.
They go on to say:
Shields is the most successful open source project I’ve ever been involved with in a major way, and for a while it didn’t contain a single line of code. I think design-savvy developers and designers have a lot to contribute to the open source world, and Shields is my proof.
Read the original blog post An Open Source Rage Diamond and visit the project itself at Shields.io.