Background

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---
schema: foundry-doc-v1
title: "Background"
slug: background-index
category: background
type: topic
content_type: topic
index_type: thematic
index_scope: background
quality: complete
short_description: "General computing concepts defined from first principles — appliances, edge and fog topology, interface design, and the security practice PointSav rejects — for a reader who wants the field vocabulary before the platform articles use it."
status: active
bcsc_class: public-disclosure-safe
last_edited: 2026-09-06
editor: pointsav-engineering
paired_with: _index.es.md
---

**Background articles** define the general computing concepts the rest of this knowledge base
takes for granted. None of them describes anything PointSav built — they are the field's own
vocabulary, written up from first principles so a reader can arrive at an architecture or
services article already holding the terms it uses. Read them in any order, or read none of
them: every platform article stands on its own.

These are meant to be browsed, not consulted. A reader who wants one platform term defined
precisely should go to the [[glossary-documentation|glossary]] instead.

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**Start here:** [[computer-appliance|Computer appliance]] — the hardware-and-software-as-one-sealed-unit pattern that the platform's own appliance images, minimal operating systems, and single-function deployment shapes all descend from.

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## Appliances and minimal systems {#group-count-4}

Purpose-built computing units and the stripped-down operating systems they run on.

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- [[computer-appliance|Computer appliance]] — Computing device pairing hardware and software engineered for one well-defined function, deployed as a sealed unit that cannot be repurposed for general computing.
- [[virtual-appliance|Virtual appliance]] — Pre-configured virtual machine image combining a minimal operating system with a specific application, distributed as a self-contained unit for compatible hypervisors.
- [[just-enough-operating-system|Just enough operating system]] — Operating system philosophy that reduces the OS to the minimum components a specific application needs, shrinking attack surface, memory footprint, and maintenance.
- [[lightweight-linux-distribution|Lightweight linux distribution]] — Linux distribution engineered to use far less RAM and processor capacity than full-featured distributions, suited to constrained, embedded, and legacy hardware.
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## Where computation happens {#group-count-2}

The distributed-topology terms for moving processing away from a central data centre.

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- [[edge-computing|Edge computing]] — Distributed computing paradigm that places computation and storage near data sources, cutting latency and bandwidth versus centralized cloud data centers.
- [[fog-computing|Fog computing]] — Distributed architecture placing compute, storage, and network services between edge devices and the cloud, defined by Cisco in 2012 and standardized as IEEE 1934-2018.
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## Interfaces and design practice {#group-count-3}

How software is addressed by other software, and how it is designed for the person using it.

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- [[application-programming-interface|Application programming interface]] — Defined interface that lets software systems communicate by specifying the available calls, how to make them, and the data formats exchanged.
- [[user-interface-design|User interface design]] — Discipline of designing human-machine interfaces to maximize usability and user experience, governed by the dialogue principles of the ISO 9241 standard.
- [[user-experience-design|User experience design]] — Multidisciplinary design practice covering every aspect of a user's interaction with a company and its products, coined by Donald Norman at Apple in the early 1990s.
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## Security practice {#group-count-1}

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- [[security-through-obscurity|Security through obscurity]] — Reliance on secrecy of design or implementation as a primary security mechanism, rejected in professional practice since Kerckhoffs' principle of 1883.
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## See also

- [Glossary and Reference](/category/reference) — the platform's own lexicon, plus the standards this wiki is written to
- [Core Concepts](/category/substrate) — the reusable mechanisms PointSav built, as distinct from the field concepts defined here
- [Security and Trust](/category/security) — what the platform does instead of relying on secrecy