GPT-5

Definition

GPT-5 is OpenAI's flagship large language model, released in 2025, unifying fast general-purpose responses with deeper reasoning modes in a single system that automatically routes requests based on task complexity.

Overview

GPT-5 succeeded GPT-4o and the o-series as OpenAI's primary model family, and its headline design change was a routing system: simpler prompts get fast answers from a lighter-weight model, while complex reasoning, math, or coding tasks are automatically routed to a deeper, more deliberate reasoning mode similar in spirit to o1 and o3. This removed the need for users to manually pick between a fast chat model and a slow reasoning model. GPT-5 is built on the Transformer architecture and trained with large-scale pretraining followed by RLHF and instruction tuning, and it supports multimodal input including text, images, and (depending on the product surface) voice and files. OpenAI positioned it as more reliable on factual questions and less prone to hallucination than earlier GPT models, alongside stronger coding and agentic tool-use capabilities. GPT-5 powers the default experience in ChatGPT and is available via the OpenAI API for developers building AI agents, coding assistants, and enterprise applications, competing directly with models such as Claude Opus and Gemini 2.5 Pro.

Key Features

• Unified model that automatically routes between fast and deep-reasoning modes
• Multimodal input support across text, images, and other modalities depending on platform
• Improved factual reliability and reduced hallucination versus prior GPT generations
• Strong coding and agentic tool-use performance
• Default model powering ChatGPT as of its release
• Available via the OpenAI API with configurable reasoning effort
• Large context window suited to long documents and multi-turn conversations

Use Cases

Frequently Asked Questions

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