OpenAI releases 'GPT-5.6' to the public, with a three-tier model lineup of Sol, Terra, and Luna

Explanation

On July 8-9, 2026, OpenAI released its new AI model family "GPT-5.6" to the public. A defining feature is its three-tier structure: "Sol," the top-tier and smartest model; "Terra," a cost-effective model for everyday tasks; and "Luna," the fastest and cheapest option. Previously, a single model became stronger as its version number increased, but this release shifts to the concept of "multiple purpose-specific tiers within the same generation." Before the public release, access was limited to a select group of trusted organizations at the government's request, but after additional safety verification it has now been made available to everyone. The idea of choosing an AI according to one's purpose is similar to choosing a smartphone plan.