Figure 1.

Timeline of mainstream LLMs commercially available to the public. The technological evolution of LLMs, highlighting several key technologies and models. It includes RNNs and LSTMs from the 1990s, Google’s Transformer model introduced in 2017, Google’s BERT model released in 2018, and the GPT series by OpenAI. Specific emphasis is placed on three major milestones: the first open-source LLM—GPT-2, and the first widely acclaimed LLM—GPT-3. These developments signify major advancements in LLMs within the field of natural language processing. BERT: Bidirectional Encoder Representations from Transformers; LLM: large language model; LSTM: long short-term memory network; RNN: recurrent neural network.