The text discusses building a search engine with the GPT-3 model, specifically using Haystack, an open-source framework for applied natural language processing. The GPT-3 model is exceptionally good at understanding implication and intent, but can still make massive mistakes and hallucinate answers that sound sensible but lack factual accuracy. To use GPT models safely and generate value, one can connect the generative model to a textual database with curated content, such as product reviews or research papers. Haystack allows users to leverage multiple GPT models in their pipeline, making it easy to build different flavors of NLP systems. The GenerativeQAPipeline is used to create a generative search engine that uses the GPT-3 model to present results in natural language. The system can handle queries with parameters such as top_k, which determines the number of documents retrieved and answers generated. The output of the GPT-3 model can be context-dependent, and it's recommended to fact-check its answers. In contrast to extractive QA models, generative QA models have better conversational skills but may hallucinate answers, while extractive QA models are more transparent but less effective in producing comprehensive answers. Haystack provides a modular building block approach for NLP systems, allowing users to build the system that best suits their specific problem.