Compiled programming languages are those that historically usually use compilers to compile source code, to output object (machine) code, usually in batches (batch mode) in a four step/phase edit-compile-link-debug cycle. This makes programming slower and less productive, but usually produces faster running programs (object code). JIT (Just In Time, or dynamic) compilers act like interpreters, but compile (not interpret) source code as they run. They can turn interpreted languages into compiled ones, and can be written for any language. But the basic difference persists: interpreted languages, and JIT compilers, make more decisions, do more work, at runtime than compiled languages. On this page, languages are arranged in three groups and levels: 1) Top group: issues spanning multiple unrelated languages. 2) Middle group: types or classes of languages. 3) Bottom group: specific languages, with their own directory category.