Instance
(Of a general purpose SNARK). The public inputs/outputs of a circuit.
In a general purpose SNARK, we call the instance the collection of public values, whether they are inputs, or desired outputs of some computation.
“Instance” is sometimes used interchangeably with the term “statement” although these terms are not exactly the same1.
1
The terms instance, witness and statement come from complexity theory and the study of relations. Read more in our introductory article