Explanation:
LRU (Least Recently Used) is a page replacement algorithm used in operating systems to manage memory efficiently. When the system needs to replace a page in memory, LRU selects the page that has not been accessed for the longest period.

LRU approximates the optimal page replacement strategy by tracking page usage over time. This algorithm is particularly effective in scenarios where recent data is likely to be accessed again.

It is widely used in memory management, caching mechanisms, and virtual memory systems.

Formal Definition:
LRU (Least Recently Used) is a page replacement algorithm that removes the least recently accessed page from memory to make room for new pages, optimizing memory usage and reducing page faults.

Additional Information:
While LRU provides better performance than simpler algorithms like FIFO, it has a higher implementation complexity due to the need for tracking page access history.

Modern implementations of LRU often use linked lists, counters, or hash tables for efficient tracking. It reduces the page fault rate compared to algorithms like FIFO in practical applications.