CSP
In plain terms
A policy controlling which resources a page can load.
Going deeper
Content Security Policy restricts the sources of scripts, styles, and other content a page may load, mitigating XSS and injection. It whitelists trusted origins.
Under the hood
Delivered via headers; nonces/hashes allow specific inline scripts while blocking the rest.
Examples
XSS prevention, script-src directives, web security, nonces, headers.
Think of it like...
Like a guest list specifying exactly which outside resources a page is allowed to invite.