CRO Glossary
Sticky Header
A navigation bar or CTA element that remains fixed at the top of the viewport as the user scrolls down the page.
A sticky header (or sticky nav) stays pinned to the top of the screen while the rest of the page content scrolls underneath it. It typically contains navigation links, a logo, and often a persistent call-to-action button, ensuring key actions or information remain accessible no matter how far a user scrolls.
CRO teams test sticky headers because they reduce the friction of having to scroll back up to find a CTA, search bar, or menu — particularly on long-form landing pages, e-commerce category pages, or content-heavy sites. Keeping the conversion path visible at all times can lift click-through rate on the CTA, especially on mobile where screen real estate is limited and scrolling is the default interaction.
A common test setup pits a standard (non-sticky) header against a sticky version with a condensed CTA button, measuring clicks on that button and downstream conversion rate. E-commerce sites often test a sticky 'Add to Cart' bar that appears once the user scrolls past the main product image.
The trade-off to watch is screen real estate: on mobile, a sticky header eats into already-limited vertical space, which can suppress content visibility or feel intrusive if it's too tall or reappears aggressively. Teams often test different trigger points (e.g., sticky only after scrolling past the fold) to balance persistence with intrusiveness.
Related terms
Above vs Below Median Split
A segmentation technique that divides users into two groups at the median of a metric to compare high and low engagers.
Qualitative Feedback Loop
A recurring process of collecting and acting on user comments, session recordings, and survey responses to inform test hypotheses.
Experiment Metadata
The structured record of who, what, when, and how for a test — hypothesis, owner, dates, variants, and metrics used to track and audit it.
Pre-Test Analysis
The upfront work of validating traffic, metrics, and baseline data quality before launching an experiment.
Above-the-Fold vs Below-the-Fold Messaging Hierarchy
How the order and prominence of value-proposition messaging is split between the visible screen and the rest of the page.
Experiment Contamination
When a control or variant group is unintentionally exposed to the other condition, corrupting the comparison.
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