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Definitions beginning with Z
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Design, UX and accessibility
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z-index
A CSS property involved in stacking order within a context. A very large value does not necessarily place an element above content in a different stacking context.
Reference: MDN : z-index · Source consulted 2026-10-18
In practice: Document a layer scale and test overlap with menus and dialogs open.
Guide: Organize a consistent website design system → Also searched as : css stacking
Zero trust
Approach basing access decisions on verification and least privilege, without granting implicit trust solely because of network location.
Reference: NIST · SP 800-207 · Zero Trust Architecture · Source consulted 2026-10-31
Source consulted : NIST CSRC · Zero Trust · 2026-10-31
In practice: Define which access is checked for each task and how it is revoked.
Guide: Manage accounts, permissions and access recovery → Also searched as : zéro confiance
SEO, search and visibility
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Zero-click search
Search ending without a click to an external result because the answer or action is available directly in the interface.
In practice: Assess the value of an answer visible without a click and measure later actions separately.
Guide: Validate structured data on a website → Also searched as : recherche sans clic
Zero-day vulnerability
Vulnerability still unknown to the vendor, with no vendor fix. A previously fixed flaw left unpatched locally is a different situation.
Reference: Canadian Centre for Cyber Security · Zero day · Source consulted 2026-10-31
In practice: Assess exposure and temporary mitigations while awaiting a verified fix.
Guide: Manage accounts, permissions and access recovery → Also searched as : faille zero day
Zero-party data
Information a person chooses to provide directly, such as a preference, need or stated intention.
In practice: Ask for a preference only when it clearly improves the service and can be changed later.
Guide: Audit and enrich directory or catalogue data → Also searched as : donnée déclarée préférence
ZIP compression
Archiving method grouping and compressing one or more files in a ZIP container.
In practice: Check contents, extracted size and folder structure before distributing an archive.
Guide: Test website navigation and menus → Also searched as : archive zip