Explore the evolution and architecture of transformer-based language models in this comprehensive lecture covering Bidirectional Encoder Representations from Transformer (BERT), Generative Pre-Trained Transformer (GPT), and their subsequent iterations including GPT-2, GPT-3, GPT-4, and T5. Gain deep insights into how these revolutionary models have transformed natural language processing and understanding, with detailed explanations of their underlying mechanisms, architectural differences, and practical applications in the field of deep learning.