UI (User Interface)
The means through which a person operates a system, including graphical elements, text, touch or voice. UI is part of user experience; button appearance does not account for all UX.
Definition and sourcesKNOWLEDGE / FROM A TO Z
Glossary
Technology, explained clearly. Find a term, choose a letter or narrow the topic. Definitions include sources and their review date.
Terms 685 / 685
Unit tests
Tests of a small unit of code behaviour. They should detect meaningful regressions; mirroring implementation in assertions can create false confidence.
Definition and sourcesUnpublished ad post
An advertising post not published as an ordinary profile post and targeted to an audience. This does not make it invisible in platform transparency tools.
Definition and sourcesUpselling
Offering a more capable or expensive version of the selected product. It should fit the need and differs from selling a separate complementary product.
Definition and sourcesUptime monitoring
Periodic service-availability checks from defined locations. Reports depend on frequency and criteria; monitoring on the same VPS can fail alongside it.
Definition and sourcesURL (Uniform Resource Locator)
An address identifying a resource and how to access it. It can include a scheme, host, path, query and fragment. Not every URL has every component, and multiple addresses can reach the same resource.
Definition and sourcesURL Rating
Ahrefs' metric for the relative backlink-profile strength of a specific URL. It differs from Domain Rating and is not a Google score.
Definition and sourcesUser journey
A description of user steps, goals and difficulties in context. Journey maps should be research-based; an ideal imagined path does not replace observation.
Definition and sourcesUser-Agent
A header describing the client's declared software, such as a browser or crawler. It can be spoofed and should not be sole identity proof.
Definition and sourcesUser-generated content
Content created by users, such as comments and reviews. It needs moderation, abuse controls and publishing rules and is not automatically trustworthy.
Definition and sourcesUX (User Experience)
A person's experience with a product, service or organisation, including understanding, usability and feelings before, during and after use. UX extends beyond screen aesthetics and digital products.
Definition and sourcesVarnish Cache
An HTTP caching reverse proxy and accelerator. Cookie, authentication and private-content rules need care to prevent cross-user data exposure.
Definition and sourcesvBulletin
Commercial forum and community software. Features, hosting and updates depend on the chosen product and licence terms.
Definition and sourcesVector graphics
Images represented by geometric objects and parameters, such as curves, allowing scaling without pixel-grid limitations. A vector file can still contain embedded raster images. “Vector” also has a separate mathematical meaning.
Definition and sourcesVersion control
Recording file-change history and collaborating on versions. It supports comparison and code recovery but does not replace whole-environment backups.
Definition and sourcesVersioning
Assigning identifiers to releases or changes under a defined policy. SemVer relates numbers to API compatibility, but not every project follows identical rules.
Definition and sourcesViewport
The visible document area in a browser. It need not equal physical screen resolution; zoom and on-screen keyboards can change available space.
Definition and sourcesVirtual DOM
An in-memory UI representation used to plan real DOM changes. It is an implementation technique, not an automatic performance guarantee.
Definition and sourcesVirtualisation
Creating logical environments on shared physical resources. Isolation and guaranteed resources depend on technology and configuration rather than the VPS label alone.
Definition and sourcesVolumetric attack
An attack overwhelming connectivity or infrastructure with traffic volume. Mitigation generally needs filtering upstream of the overloaded resource, not just application-server rules.
Definition and sourcesVPN (Virtual Private Network)
A virtual private network connecting devices or networks through other infrastructure. Common implementations encrypt traffic to the VPN endpoint. It provides neither complete anonymity nor phishing protection; tunnel scope and provider trust matter.
Definition and sourcesVPS (Virtual Private Server)
A virtual server with its own operating environment on shared physical infrastructure. Guaranteed resources depend on the offer. The label alone determines neither cost nor performance; administration, backups and monitoring also matter.
Definition and sourcesVue.js
A JavaScript framework for declarative component interfaces. It supports different project sizes; complete architecture still needs data and routing decisions.
Definition and sourcesWCAG (Web Content Accessibility Guidelines)
W3C accessibility guidelines. WCAG 2.2 defines testable criteria and levels A, AA and AAA. A conformance claim needs assessment of the proper scope; automated checks alone cannot confirm every criterion.
Definition and sources