Bootstrapping is a computer science method to create a programming language, that is compiled with itself. In most cases, a compiler is written in a language, where the compiler is rewritten for the language that is being compiled.
Most popular programming languages all follow a pattern of bootstrapped compilers. Some include Java, C#, C, Rust, Ruby, Python, and more.
Process
Bootstrapping usually has just a few stages:
Build & prepare tools, and software to create a bootstrap compiler. Stage 1: Create a compiler for your programming language using another language, or whatever tools you have. This will be used to compile your final compilers. Stage 2: Use your created compiler to recreate your original compiler. This should be identical to a stage 1 compiler. Stage 3: Any newly added features would be added at stage 2, where the language is now only written in itself, and is compiled using a compiler, compiled in the same language.
Early Bootstrapping
In 1962, Tim Hart, and Mike Levin wrote a compiler for LISP, inside of LISP. They improved the compiler until it was capable of compiling itself.