ChatGPT takes text prompts and generates coherent, contextually relevant responses across writing, coding, analysis, and creative tasks. It arrived in late 2022 as the first mainstream interface to GPT technology, fundamentally shifting how people think about AI assistance. The free tier runs on GPT-3.5; paid subscribers ($20/month) access GPT-4, which handles longer context and harder reasoning. The core limitation remains unchanged: it can confidently produce plausible-sounding but entirely false information, and it has no access to real-time data or the internet.