A dentry is the glue that holds inodes and files together by relating inode numbers to file names. Dentries also play a role in directory caching which, ideally, keeps the most frequently used files on-hand for faster access. File system traversal is another aspect of the dentry as it maintains a relationship between directories and their files.

The differences between dentry and inode are that dentry is used to facilitate directory-specific operations, inode is just a collection of metadata about files and directories. Superblock is the abstraction of filesystem.