Tor: What can a website see when I visit through Tor?

Short answer

A normal website sees the Tor exit relay's IP address rather than your home IP address. It can still see information you submit, such as an account login, messages, purchases, or identifying details. Tor Browser also reduces browser fingerprinting, but no browser can erase what you voluntarily disclose. Use HTTPS so the exit-to-website connection is protected as well.

Sources

Tor Project: About Tor Browser, Tor Project: Secure connections.