【Tech 24H】OpenAI has announced the removal of message caps for free tier and Go tier users in pure text-based conversations. This adjustment means free users can now engage in unlimited text chats without the previous usage constraints. The core change brought by this update is that GPT-5.6 Luna will replace GPT-5.5 Instant as the default model for free and Go tier users. Luna is the smallest model in the GPT-5.6 series, built for fast response times and low costs, with enhanced performance in language comprehension, logical reasoning and content generation compared with its prior version. Additionally, ChatGPT rolled out a new "Think" button for free users. When tackling complex questions, users can click this button to let the model allocate more computing resources for in-depth reasoning, generating more precise responses. This feature comes with no usage limits for plain text interactions. However, it is still bound by individual quota limits when paired with file upload, image input and other multimedia functions. [ By Zhang Liyan ]