Frontier Model

A frontier model is one of the most capable AI models at the cutting edge of what's technically possible at any given moment. In mid-2026 the frontier includes GPT-5.6 Sol, Claude Opus 4.8, Claude Mythos 5, Gemini 3.5 Pro, and Llama 4 Behemoth. Frontier models share characteristics: trained at very large scale (hundreds of billions to trillions of parameters), capable across a wide range of tasks, exhibit emergent abilities not present in smaller models, and increasingly gated by capability-based safety reviews (GPT-5.6 and Mythos 5 both have restricted access in 2026). The term is contested — there's no formal definition — but the rough rule is "models that score in the top tier across coding, reasoning, multimodal, and long context benchmarks at the time of release."