Semantic search is a task of retrieving documents from a collection in response to a query asked in natural language, using the latest Transformer language models. It's a powerful tool for searching large collections of documents and can be used in various applications such as question answering, text summarization, and more. Python has become the principal language for machine learning and NLP tasks, and Haystack is a framework for applied NLP that uses a modular, mix-and-match approach to building NLP systems. With Haystack, users can set up a semantic search system in under 20 minutes using pre-trained models and high-quality document store like FAISS. The framework offers flexibility and customization options, making it suitable for various use cases. It's also extensible, allowing users to add custom nodes such as ranker or summarizer to improve results. Haystack is an open-source project with a vibrant community and extensive documentation, making it the go-to choice for Python developers looking to implement semantic search systems.