The document discusses MapReduce algorithm for analyzing big data. It defines MapReduce as a programming model and software implementation for processing large datasets in a distributed computing environment. The key aspects covered are: - MapReduce was invented by Jeff Dean and Sanjay Ghemawat at Google as a way to process massive amounts of data in parallel across clusters of computers. - It works by breaking the processing into two phases - the map phase where the data is processed key-value pairs and the reduce phase where the outputs of the map phase are aggregated together. - MapReduce provides scalability, flexibility, and fault-tolerance for distributed computing on large datasets and has applications in web analysis, internet security, personalized services and