Microsoft has announced significant updates to its Copilot service, integrating advanced AI models across its different tiers. The company has opened its Copilot GPT Builder to all Pro subscribers, allowing for the creation of custom GPT models similar to ChatGPT. Additionally, the free version of Copilot has been upgraded to GPT-4 Turbo, replacing the previous GPT-4 model. This upgrade is available to users in 169 countries, providing free access to a top language learning model (LLM). Pro users have the option to continue using the older GPT-4 model if they prefer. The introduction of GPT-4.5 Turbo has also been hinted at, with claims of improved speed, accuracy, and scalability over its predecessor, GPT-4 Turbo, and it is noted for its 256k context window.