GPT-4 was OpenAI's fourth-generation large language model, released in March 2023. It was the model that established the commercial viability of enterprise AI products — substantially more capable than GPT-3.5 at reasoning, coding, and following complex instructions, while maintaining the conversational interface that ChatGPT had popularized.
GPT-4 and its successors (GPT-4 Turbo, GPT-4o, GPT-4.1) dominated enterprise AI deployment through 2023-2024. By 2025 the model had been displaced at the capability frontier by Claude Opus 4 and Google Gemini 2.0, but GPT-4 variants remained widely deployed because of OpenAI's distribution and the switching cost of rebuilding integrations.
As of 2026, GPT-4 has been succeeded by GPT-5 and its variants. OpenAI has deprecated most GPT-4-era endpoints but maintains backward compatibility layers for enterprise customers on long-running contracts.