ChatGPT offers several ways to customize and personalize your conversations. You can share your name, your profession, and other tidbits about your life. You're able to tell it what traits it should possess, such as patience, sympathy, or understanding. You can add and save certain facts about yourself and tell it to reference memories from past conversations.That all sounds helpful. But what does ChatGPT do with the information it knows about you? I shared certain details about myself and my life to find out. Here's what happened.Also: Is ChatGPT Plus really worth $20 when the free version offers so many premium features?First, I'll cover the ways that I customized and personalized ChatGPT. You can do this at the ChatGPT website, in the Windows or Mac app, or in the iOS or Android app. I found it easiest to do this at the website and the Windows app.Before we move ahead, always be careful what personal information you share about yourself with ChatGPT or any AI. OpenAI promises that the details aren't accessible to staff members or are at least anonymized. Still, you'll want to be cautious. Share just enough about yourself to make the conversations more personalized and interesting. But don't reveal anything you wouldn't want another person to know about you.(Disclosure: Ziff Davis, ZDNET's parent company, filed an April 2025 lawsuit against OpenAI, alleging it infringed Ziff Davis copyrights in training and operating its AI systems.) In another conversation, I asked ChatGPT to name some places where I can get my favorite drink in my favorite city. In response, it showed me a list of restaurants and shops in New York City where I could order a chocolate egg cream. It then displayed a map with the location of each spot on the list. Finally, here's where ChatGPT got really clever. I asked it to define a tachyon, a hypothetical particle that can move faster than the speed of light. The AI defined the word and then showed examples of tachyons in "Star Trek" and "Doctor Who," two of my favorite TV shows.Also: How to use ChatGPT's Voice Mode (and why you'll want to)It then offered to write a short sci-fi story involving tachyons, time travel, and Mr. Giggles, my cat. The resulting story was fun and creative. From there, ChatGPT could turn it into a full short story, a comic script, or an audio drama outline.I didn't tell the AI to incorporate Mr. Giggles into the conversation; it did that on its own. But this shows the surprises that can pop up when you share just enough about yourself with ChatGPT. Get the morning's top stories in your inbox each day with our Tech Today newsletter.