Memoization is an optimization technique used in computer science to speed up the execution of functions by storing the results of expensive function calls. When a function is called with a specific set of inputs, the result is saved in a cache. If the same inputs are used again, the function can return the cached result instead of recalculating it, which saves time and resources. This technique is particularly useful in scenarios involving recursive functions, such as those found in algorithms for calculating Fibonacci numbers or solving problems in dynamic programming. By reducing redundant calculations, memoization enhances performance and efficiency in various applications.