In Unix, i-nodes (index nodes) are used to record the actual physical file and its location, while the file name is just a link pointing to the i-node. Therefore, each file can have multiple names, and each name is considered a link to the file. All links of the same file point to the same i-node. However, when deleting, all the links to the i-node must be removed before the i-node itself can be deleted, which in turn deletes the file itself.