Efficient algorithms refer to algorithms that are designed to solve problems in an optimal way, using the least amount of resources such as time and memory. These algorithms are typically designed to be fast, scalable, and able to handle large amounts of data efficiently. Efficiency is measured in terms of the algorithm's time complexity, space complexity, and overall performance. Researchers in this area focus on developing and analyzing algorithms that can solve complex problems effectively, often using techniques such as dynamic programming, greedy algorithms, and divide and conquer strategies. The goal of efficient algorithms research is to improve computational efficiency and find faster and more effective solutions to a wide range of problems.