Redis is a Data Structure Store that allows dealing with Key-Value Pairs as well as data structures such as Hashes, Lists, Sets, and Sorted Sets. It leverages the power of these data structures to support operations like exact match queries through hashes and range queries through sorted sets. Redis also supports Modules, including RediSearch for full-text indexing and searching capabilities. The complexity of accessing an entry in a hash or a sorted set is O(1), while the complexity of scanning a sorted set is O(log(n)+m).