A home directory is a file system directory on a multi-user operating system containing files for a given user of the system.
As defined by Wikipedia: "A home directory is a file system directory on a multi-user operating system containing files for a given user of the system." Although specifics may vary from system to system, a general convention is that executable programs and system wide configurations are stored in shared directories while users' home directories are reserved for their personal information, be it password files, documents or even source code they're developing.