Modules are the method YARA provides for extending its features. They allow you to define data structures and functions which can be used in your rules to express more complex conditions. Here you'll find described some modules officially distributed with YARA, but you can also learn how to write your own modules in the writing-modules section.
PE <modules/pe> ELF <modules/elf> Cuckoo <modules/cuckoo> Magic <modules/magic> Hash <modules/hash> Math <modules/math> Dotnet <modules/dotnet> Time <modules/time>