"JIT" stands for Just-In-Time in programming languages. This is a compilation technique where code is compiled into machine language at runtime, rather than beforehand. JIT compilers optimize the performance of applications by allowing them to execute faster, as they can adapt to the current execution context and make optimizations dynamically. This approach is commonly associated with languages like Java and C#, enhancing efficiency while balancing the overhead of runtime compilation. JIT can significantly improve the performance of applications that require quick, on-the-fly execution.