Transformer Models revolutionized artificial intelligence by replacing recurrent architectures with self-attention, enabling parallel processing and long-range context understanding. These innovations laid the foundation for today’s Large Language Models (LLMs) such as GPT, BERT, and T5, which power chatbots, translation systems, and code assistants. This article explores how Transformers work, how LLMs are trained, and how they’re transforming industries through advanced natural language processing, generation, and reasoning while also addressing their challenges in bias, alignment, and energy efficiency.