Least Frequently Used (LFU) is a cache replacement algorithm that prioritizes keeping data that is accessed most often. When the cache reaches its limit, LFU removes the item that has been used the least number of times. This approach helps ensure that frequently accessed data remains available, improving overall system performance. In LFU, each item in the cache is associated with a counter that tracks how many times it has been accessed. When a new item needs to be added, the algorithm compares the counters and evicts the item with the lowest count. This method is particularly useful in scenarios where certain data is consistently more relevant than others, such as in database management or web caching.