FrontendHigh signal
Hydration
Also written as Client-Side Hydration
The process of a server-rendered page 'waking up' in the browser — JavaScript attaches to the already-rendered HTML and makes it interactive, instead of building the page from scratch.
Think of it like
Like a mannequin in a store window that looks fully dressed and ready, then suddenly comes to life and starts responding to customers.
Junior or senior?
Junior sounds like
Has seen a hydration error in the console without knowing what caused it.
Senior sounds like
Can explain a hydration mismatch they debugged and what caused the server and client output to differ.
Ask them
“Tell me about a hydration mismatch bug you've debugged. What caused the server and client output to differ?”