BERT (Bidirectional Encoder Representations from Transformers) is a general language model that has greatly improved the standard for language models, revolutionizing natural language processing (NLP). Designed by Google researchers in 2018, BERT uses the Transformer architecture and adapts it to process written language at a near-human level. Its ability to capture context makes it useful for various downstream tasks like question answering, sentiment analysis, and more. The model's success led to numerous variants, including RoBERTa, Polyglottal BERT, BioBERT, SciBERT, and others. These models have been fine-tuned for specific domains, such as finance, healthcare, and social media, enhancing their performance in those areas. Researchers continue to push the boundaries of BERT by exploring new training tasks, model distillation, and multimedia models, aiming to improve its semantic generalization and performance on individual tasks.