Why does NULL = NULL evaluate to false in SQL server

Question

In SQL server if you have nullParam=NULL in a where clause, it always evaluates to false. This is counterintuitive and has caused me many errors. I do understa

Answer 1

Just an addition to other wonderful answers:

AND: The result of true and unknown is unknown, false and unknown is false,
while unknown and unknown is unknown.

OR: The result of true or unknown is true, false or unknown is unknown, while unknown or unknown is unknown.

NOT: The result of not unknown is unknown