You Have Two Computers Connected By An Ethernet Hub At Home. Is This A LAN, A MAN, Or A WAN?

These Small sizes networks are categorized to LAN. Ethernet is a LAN. All small sized office networks and in-house networks are LANs. MAN owned by single company, it's averagely large network. Participate Level2 (eg: Switches) networking devices. (Level 3 also can contain).  A Man is a Metropolitan Area Network - that connects together all machines  in an enterprise, campus or town.

A WAN is a Wide Area Network that typically connects machines that are geographically remote. WAN interconnect several sub networks together. It's a large network. Usually Network resources are owned by several companies. Heavily consist with Level 3 networking devices (eg: Routers). Expand to large geometric areas.