Icons that are in uniform and simple have been developed in chucks over time, but now there are libraries being built. Once a library is constructed there is greater attention to what’s all included, what’s missing, and possibly know if there will be more styles or collections.
These icon libraries such as The Noun Project, Pictos, and Symbolicons to name a few are being crucial resources for any UI or UX designer striving for simplicity, character, and uniformity. The attention to choice of icons has never been higher before.
With rising popularity comes debates over the mission, ideas, and methods behind these libraries.
The Noun Project creates and collects icons that show simplicity, look great, and easy to recognize and understand. The level of uniformity lies in them following those guidelines. That’s it. They do have collections which are more like themes rather than styles.
Then there is Pictos (Symbolicons is similar). Here they are focused more on the style being in uniform than just them looking great and being recognizable and easy to understand. A sense of character is felt among each collection and currently there are five different collections in the Pictos library. These collections are more different styles than themes.
How these icons are created and then organized is a role the library must play and be responsible for. Now, whether that should be more theme or style based is up to the each library.
As the amount of icons continue to grow and develop, edits should be made to ensure that each collection is properly organized. Unless of course the library chooses to organizes by a date archive system.