Term
Non-Volley Zone Line
Also called: Kitchen Line, NVZ Line
The line between the kitchen and the service court. It counts as part of the kitchen.
The line across the court between the kitchen and the service court (3.A.4.c). The kitchen line is part of the kitchen (3.A.4.c).
So if you volley while standing on the line, it is a fault (11.A.1). A serve that touches this line is also a fault (7.E.2, 8.C, A serve that touches the kitchen line is a fault).
See it in a figure
This figure is from the rule "A serve that touches the kitchen line is a fault".
How to read the sources: numbers like (8.F.4) are rulebook sections, and links are outside sources. An "Author's note" is the author's personal experience, not an official rule.