OpenAI announced GPT-5.6 today, moving to a naming structure where generation numbers pair with durable model tiers rather than incremental point releases. The new family includes Sol as the flagship, Terra for everyday work, and Luna as the fast and affordable option, marking a shift away from the rapid version cadence of GPT-5, 5.1, 5.2, 5.3, 5.5, and 5.6 over the past year.