Modelbuilder is often an afterthought to most GIS analysts, however, it can be a powerful tool when it comes to building and replicating complex workflows, as well as automating those boring, tedious tasks.
Iterators are unique to models, and allow you to loop through a process on unique values, tables, layers in your map document, or even workspaces.
Let’s have a look at iterators, and how you can use them.
Esri Australia Technical Blog 