Which language is used to create another programming language?

Answer 1

Usually C or C++ for performance.

Answer 2

For interpreted languages, it's usually C.

For compiled languages, the compiled languages are usually written in the language itself. The C/C++ compiler GCC was written in C and now it is written in C++. The Go compiler is written in Go. The C# compiler is written in C#. The Java compiler is written in Java. And so on.