Retrieval-Augmented Generation (RAG) has become a pivotal approach in enhancing large language models with external knowledge, relying heavily on advancements in embeddings and reranking technologies to improve information retrieval. Traditional keyword-based search systems like BM25 have limitations due to vocabulary mismatches, which embeddings address by transforming words into vector spaces that capture semantic relationships. The introduction of transformer-based models allows for dynamic, context-aware embeddings, enhancing the retrieval quality for complex queries. In RAG systems, reranking plays a crucial role by refining the retrieval process, first employing broad retrieval methods to gather potential documents and then using rerankers to evaluate and precisely rank these documents based on their relevance to the query. Different industries apply RAG systems uniquely, with legal tech focusing on authoritative documents, healthcare emphasizing clinical context, e-commerce optimizing for multi-dimensional relevance, and finance accounting for temporal changes. The interplay between embedding quality, retrieval architecture, and reranking strategy is essential for building effective RAG systems, which must be tailored to specific domains and user intents to truly define relevance in context.