Omega Notation is a mathematical concept used in computer science to describe the lower bound of an algorithm's running time. It provides a way to express the minimum amount of time or space an algorithm will require as the input size grows. This helps in understanding the efficiency of algorithms, especially in the worst-case scenario. In formal terms, if a function f(n) is said to be in Ω(g(n)), it means there exist positive constants c and n₀ such that for all n ≥ n₀, f(n) ≥ c * g(n). This notation is essential for analyzing algorithms and comparing their performance.