What is a cookie banner?
A cookie banner is the on-site UI that asks visitors for consent to set non-essential cookies. It exists to meet consent standards under the GDPR and ePrivacy rules: consent must be freely given, specific, informed, and unambiguous. In practice, that means no pre-ticked boxes, no “nudging” users to accept, and rejecting should be as easy as accepting.
How do cookie banners work?
On the first pageview, the banner (first layer) offers three clear actions: Accept all, Reject all, or Customize. The preferences modal (second layer) lets users toggle purposes (e.g., analytics, ads, functional) and see which vendors may receive data. The system records a consent event with timestamp and (if used) a privacy-safe identifier like a Client ID. Tags then read the consent state before firing, so analytics and ad scripts behave according to user choice. For sites using privacy-first, cookieless analytics tools (e.g., Plausible, Matomo, Simple Analytics), you may reduce or avoid consent prompts for measurement that doesn’t set non-essential cookies—validate this against your local guidance.
Implementation checklist
- Symmetry: “Reject all” shown with equal prominence to “Accept all.”
- Granularity: Group by purposes; avoid blanket consent.
- No dark patterns: Clear copy, balanced buttons, obvious “Continue without consent.”
- Proof & lifecycle: Log consent state, provide an always-visible “Change consent” control, and refresh consent when purposes change or after expiry.
- Regionalization: Only show banners where required; honor signals across devices where feasible (see Cross-Device Tracking and Cross-Platform Tracking).
- Measurement: Track consent interactions as an event and monitor impacts on engaged sessions, conversion, and UTM attribution quality.
Common mistakes
- Hiding “Reject all” behind multiple clicks.
- Setting non-essential cookies before consent.
- Using vague labels (“Enhance experience”) instead of plain-language purposes.
- Forgetting first-party scope (see First-Party Cookie) and vendor lists.