The main purpose of this category of posting is to learn often-used styles of Mma coding. I learned the majority of these by reading the code written by Maeder, Trott, Wolfram & Gray.
Sometimes they are used for their economy. In other situations they can just be quickly recognized and even if they are not shorter, they are shortcuts for the reader. They are often but not always in the functional propgramming style.
Unfortunately they mainly server this function for the initiated. This postings in this cateory attempt to broaden this audience.