o1
By OpenAI
o1 is OpenAI's first publicly released 'reasoning' model, launched in 2024, trained to work through complex problems step by step using extended internal reasoning before producing a final answer.
Definition
o1 is OpenAI's first publicly released 'reasoning' model, launched in 2024, trained to work through complex problems step by step using extended internal reasoning before producing a final answer.
Overview
o1 introduced a new model category for OpenAI, distinct from the standard GPT line: rather than optimizing purely for fast, fluent responses, o1 is trained to spend additional computation reasoning through a problem internally — sometimes described as 'thinking longer' — before returning an answer. This approach produced substantial gains on tasks with objectively verifiable answers, such as competition mathematics, coding, and scientific reasoning benchmarks, where earlier GPT models were more prone to logical errors. The extended internal reasoning process in o1 is generally not shown to users in full; instead, a summarized version of the reasoning may be surfaced while the detailed chain of thought remains hidden, partly for safety and partly to prevent the reasoning process itself from being easily copied. This tradeoff means o1 is typically slower and more expensive per query than models like GPT-4o, making it best suited to problems where accuracy matters more than speed. o1 was followed by o3 as OpenAI iterated on the reasoning-model paradigm, and the underlying approach — allocating more inference-time computation to harder problems — was eventually folded into the unified routing behavior of GPT-5.
Key Concepts
- Extended internal reasoning ('thinking') before producing a final answer
- Strong performance on math, coding, and scientific reasoning benchmarks
- Detailed chain of thought generally hidden from the user by design
- Higher latency and cost per query than standard chat models
- Distinct model line from the standard GPT family
- Predecessor to OpenAI's o3 reasoning model