Anatomy of a panel of horizontal (Lap) siding:

Buttlock: The bottom edge of a siding panel that locks into the panel below it

Center butt : a joint or connection at the center of a siding panel.

Face: The visible part of the siding after it’s installed

Exposure: The width of the exposed face of a siding panel

Nail flange: A flat area along the top of a siding panel with slots for nailing

Rows: The image above shows a panel of lap sding with 2 rows. 

Weep hole: An opening cut into the siding to allow water to run off,

Anatomy of a panel of vertical (Board and Batten) siding:

Board: The wide vertical portion of the panel of siding.

Batten: The thin vertical portion of the panel of siding that covers nailing flange of the previous piece of siding.

Face: The visible part of the siding after it’s installed

Exposure: The width of the exposed face of a siding panel

Nail flange: A flat area along the top of a siding panel with slots for nailing