GPT-4 Architecture and Capabilities

GPT-4, developed by OpenAI, represents a significant leap in large language model capabilities. Released in March 2023 and continuously updated since, it powers ChatGPT Plus and is available through OpenAI's API for developers.

GPT-4's architecture builds on the Transformer model with several key innovations. While OpenAI has not disclosed the exact model size, it is widely estimated to use a Mixture of Experts (MoE) approach with approximately 1.8 trillion total parameters, though only a subset is active for any given query. This design allows for greater capability while managing computational costs.

Key capabilities that distinguish GPT-4 include multimodal understanding (it can process both text and images as input), extended context windows (up to 128K tokens in GPT-4 Turbo, equivalent to roughly 300 pages of text), improved reasoning and accuracy compared to GPT-3.5, better performance on standardized tests (scoring in the 90th percentile on the bar exam), and stronger code generation across multiple programming languages.

GPT-4 is available in several variants. GPT-4 is the base model with an 8K context window. GPT-4 Turbo offers a 128K context window at lower cost. GPT-4o (omni) adds native multimodal capabilities including voice and vision. GPT-4o mini provides a cost-effective option for simpler tasks.

For developers, GPT-4 is accessible through the OpenAI API with features like function calling (allowing the model to interact with external tools), JSON mode (ensuring structured output), and fine-tuning capabilities. Pricing is based on input and output tokens, with costs varying by model variant.

Limitations include occasional hallucinations, a knowledge cutoff date, potential biases from training data, and the inability to access real-time information without plugins or function calling. Despite these limitations, GPT-4 remains one of the most capable AI models available and continues to be improved through regular updates.