What you need to know
Hydration warnings often come from reading browser-only values, random numbers, current time, or locale-dependent output during initial rendering. The server and browser can produce different markup.
How to apply it
Keep initial output deterministic, move browser-only work into an effect, or render a stable placeholder until required client information is available. Check the exact element named in the warning.
Common mistake to avoid
Do not silence hydration errors with broad suppression. It hides inconsistent content and can leave controls behaving differently from what users see.