A repository can have zero (i.e. bare repository) or one or more worktrees attached to it. One "worktree" consists of a "working tree" and repository metadata, most of which are shared among other worktrees of a single repository, and some of which are maintained separately per worktree (e.g. the index, HEAD and pseudorefs like MERGE_HEAD, per-worktree refs and per-worktree configuration file).