From Structured Computer Organization by Tanenbum
A program is a sequence of instructions describing how to perform a certain task.
When trying to see a programming language as a formal languages added with semantics, I heard that a programming language is a set of valid programs (valid according to the syntax and other aspects of the language).
When reading Structured Computer Organization by Tanenbum, I understood that a programming languages is a set of instructions, from
Each machine has a machine language, consisting of all the instructions that the machine can execute.
So I wonder if a programming language is a set of programs or a set of instructions? Thanks.