the.com/null pointer
a variable pointing at nothing, confidently, until the moment your program disagrees.
means a reference that is supposed to point to a valid memory location but instead points to nowhere, so using it crashes or errors.
from coined with the rise of pointer-based languages like c in the 1970s; tony hoare, who introduced null references in 1965, later called it his billion-dollar mistake.
inventor's regrethoare called null his billion-dollar mistake
common crashnullpointerexception is java's most infamous error
fix attemptlanguages like rust ban null entirely