What is the difference between CSR, SSR, and hydration for a React app?
PICTURE THIS: DOM IS A TREE
Simple meaning
CSR renders in the browser after downloading JS, which is the classic MERN SPA.
WHY — React instead of guessing?
Why interviewers care about React:
contrast on React, not two memorised paragraphs.
the developer, then one case where picking wrong hurts.
Name the idea, why it exists, then one short example.
End with when you use it and one common pitfall.
STEPS — What happens step by step?
Before you speak the answer, walk the interviewer through these steps:
- 1CSR renders in the
browser after downloading JS, which is the classic MERN SPA.
- 2SSR sends HTML from
a server, then hydration attaches event handlers.
- 3Hydration mismatches from random
ids or invalid HTML cause the client tree to throw away server markup.
- 4Give an example
One tiny concrete case you can say aloud.
- 5Common mistake
What juniors usually get wrong.
- 6Close
When you pick this over the alternative.
EXAMPLE — See it in action
Here's a short line you can speak, broken into clear beats:
Note: Adapt this scaffold to your own project — keep it under 60–90 seconds.
Key takeaway
CSR renders in the browser after downloading JS, which is the classic MERN SPA. SSR sends HTML from a server, then hydration attaches event handlers.