# Client-Side Validation

*noun*

say it: **“KLY-ent SYDE val-ih-DAY-shun”** **/ˈklaɪənt saɪd ˌvælɪˈdeɪʃən/**

Checking form input in the browser before it is sent, so the user sees mistakes straight away.

## What is **Client-Side Validation**?

**Client-Side Validation** — Checking form input in the browser before it's sent, so the user sees a mistake straight away. It's for convenience only: anyone can skip it, so the server checks again.

```html
<input type="number" name="price" min="0" required>
```

## In a sentence

- “**Client-side validation** told me the email was missing before the page even posted.”

Level: Apprentice · [More Web Development terms at this level](https://www.ask-codey.com/glossary?category=web-development&level=2)

Updated: October 28, 2026

Source: https://www.ask-codey.com/glossary/client-side-validation