In C++ metaprogramming refers to the use of macros or templates to generate code at compile-time.
In general, macros are frowned upon in this role and templates are preferred, although they are not as generic.
Template metaprogramming often makes use of compile-time computations, whether via templates or constexpr functions, to achieve its goals of generating code, however compile-time computations are not metaprogramming.
Metaprogramming (or more specifically, template metaprogramming) is the practice of using templates to create constants, functions, or data structures at compile-time. This allows computations to be performed once at compile time rather than at each run time.
Iterating over a parameter pack
Iterating with std::integer_sequence