Information retrieval systems are tools designed to help users find and access information from large collections of data. These systems use algorithms to search through databases, websites, or documents, returning relevant results based on user queries. Common examples include search engines like Google and library databases. These systems typically involve indexing, which organizes data for efficient searching, and ranking, which determines the order of results based on relevance. Users input keywords or phrases, and the system retrieves documents or data that match those terms, making it easier to locate specific information quickly.