what is Sysvol folder

The Sysvol folder on a Windows domain controller is used to replicate file-based data among domain controllers. Because junctions are used within the Sysvol folder structure, Windows NT file system (NTFS) version 5.0 is required on domain controllers throughout a Windows distributed file system (DFS) forest.This is a quote from microsoft themselves, basically the domain controller info stored in files like your group policy stuff is replicated through this folder structure