Just-In-Time compilation, often abbreviated as JIT compilation, is an approach in computer science and programming where the source code or an intermediate representation of a program is translated into machine code or an executable form during runtime. This translation doesn't occur in advance (as in static compilation) but rather just before the code is actually executed.

Here are some key features and advantages of Just-In-Time compilation:

1. Runtime Optimization: JIT compilation often applies specific optimizations based on current runtime conditions. This allows tailoring the generated machine code to the actual execution environment and available hardware.

2. Platform Independence: JIT compilation can help create platform-independent code since the translation of the code into machine code occurs on the target system.

3. Improved Performance: Optimized code execution can lead to better performance, especially when the code is executed repeatedly. This is common in runtime environments like the Java Virtual Machine (JVM) or .NET Common Language Runtime (CLR).

4. Avoidance of Precompilation: Unlike static compilation, where the code is fully translated before execution, JIT compilation only translates the necessary code at runtime. This can reduce startup overhead.

5. Dynamic Code Changes: JIT compilers can also support dynamic changes to the code by recompiling parts of the code when requirements change.

JIT compilation is used in various programming environments and runtime environments, including Java, .NET, JavaScript (in browsers), and many modern scripting languages. Using JIT compilation allows code to be executed in a way that combines the benefits of both interpreted and statically compiled approaches.