Volumes are data containers. In a NAS environment, they contain file systems that hold user data that is accessible using one or more of the access protocols supported by Data ONTAP, including NFS, CIFS, HTTP, FTP, FC, and iSCSI. In a SAN environment, they contain LUNs.
Volumes depend on their associated aggregate for their physical storage.
FlexCache volumes, FlexClone volumes, and SnapLock volumes are types of volumes that share some characteristics with FlexVol volumes, but also have some special capabilities and requirements.