The Haystack question answering system relies on an intricate building block called the "Reader," which processes batches of preselected documents to find the best answers to natural-language queries. The reader object is an interface to a Transformer-based language model, such as BART, BORT, or CamemBERT, and can be fine-tuned to perform extractive QA tasks. Choosing the right reader model depends on factors like computational power, performance-speed tradeoff, multilingual support, and the specific task requirements. Haystack provides two classes of readers: TransformersReader and FARMReader, with FARMReader being recommended for its usability, performance optimization, and ability to remove duplicate answers automatically. By selecting the right reader-model combination, users can build efficient and effective question answering pipelines in their Haystack systems.