System design means planning the architecture, modules, interfaces, and data flow of a system before anyone writes a line of code. In UI/UX, this planning produces what people call design system components: a shared framework that keeps products consistent and teams from reinventing the wheel every sprint.

1. Design tokens are the smallest named units in a design system. They store values for color, typography, spacing, border radius, shadows, and animation. Change a token once and every component that references it updates automatically.

2. Component library is the central repository of reusable UI elements. Each piece is built to be accessible, responsive, and themeable, and ships as a versioned code package so teams can pin to a stable release.

3. Style guide and visual language defines brand standards: logo rules, color palettes, icon sets, and type scales. Without this, two teams building the same product will make it look like two different products.

4. Pattern library goes a level above individual components. It documents how multiple components combine to solve real UX problems, like onboarding flows, error states, and search experiences.

5. Documentation and governance covers the human side. Who can propose a new component? Who reviews it? Who decides when something gets deprecated? Good docs answer the "when" and "why," not just the "how."

6. Accessibility standards mean every component has to meet WCAG 2.1 or 2.2 guidelines: sufficient color contrast, full keyboard navigation, and screen reader support. Non-negotiable.

7. Infrastructure and tooling includes version control, package managers, design tool plugins, CI/CD pipelines, and documentation platforms. The unglamorous stuff that keeps everything actually working.

These seven pieces work together to give cross-functional teams a shared language. Designers, engineers, and product managers stop arguing about button styles and start shipping features instead.