Numba is an open-source just-in-time (JIT) compiler for Python that translates Python functions and NumPy array operations into optimized machine code using the LLVM compiler. Sponsored by Anaconda, Numba specializes in numerical and scientific computing where performance is critical, offering substantial speedups (often 10-100×) with minimal code changes. The key insight is that Numba targets array-oriented numerical code particularly well—loops over NumPy arrays, mathematical computations, and parallel operations that would be slow in pure Python execute at speeds approaching C or Fortran.