Ahead-Of-Time Compilation (AOT) is a process where source code is translated into machine code before the program is run. This means that the compilation happens in advance, allowing the program to execute faster since it doesn't need to be compiled during runtime. AOT is commonly used in languages like C and C++. In contrast to Just-In-Time Compilation (JIT), which compiles code while the program is running, AOT can lead to more efficient memory usage and quicker startup times. However, it may lack some optimizations that JIT can provide during execution. Overall, AOT is beneficial for applications where performance and startup speed are critical.