Cumulative Layout Shift (CLS)
A Core Web Vital that quantifies unexpected visual movement of page elements during loading. Target is under 0.1. Caused by images without dimensions, dynamically injected content, and web fonts causing FOIT/FOUT.
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Accessibility (WCAG)
The Web Content Accessibility Guidelines (WCAG) define standards for making web content perceivable, operable, understandable, and robust for users with disabilities. WCAG 2.2 AA is the current standard, increasingly enforced by law.
AVIF
A next-generation image format based on the AV1 video codec. Offers 50% better compression than JPEG and 20% better than WebP. Supports HDR, wide color gamut, and transparency. Browser support is nearly universal as of 2025.
CI/CD Pipeline
Continuous Integration and Continuous Delivery/Deployment — automated workflows that build, test, and deploy code on every commit. Reduces deployment risk, catches bugs early, and enables multiple daily releases.
Code Splitting
A bundling technique that breaks JavaScript into smaller chunks loaded on demand. Reduces initial bundle size, improving Time to Interactive. Implemented automatically by Next.js at the route level and manually with dynamic imports.
Content Delivery Network (CDN)
A globally distributed network of servers that caches and delivers content from the location nearest to each user. Reduces latency from hundreds of milliseconds to single digits. Essential for global performance.
Core Web Vitals
Three metrics Google uses to measure real-world user experience: Largest Contentful Paint (loading), Interaction to Next Paint (interactivity), and Cumulative Layout Shift (visual stability). Direct ranking factor since 2021.