Serverless

A webhook is a mechanism where one system sends an automated HTTP request to another system when a specific event occurs. Unlike polling, where the client repeatedly checks for updates, webhooks push data in real time, making them far more efficient. They are widely used to connect services — for example, triggering a deployment when code is merged or sending a Slack notification when a payment is processed.

Progressive enhancement is a web development strategy that starts with a baseline of functional HTML content accessible to all browsers, then layers on CSS styling and JavaScript interactivity for more capable environments. This approach ensures that core functionality works everywhere, while users with modern browsers get a richer experience. It contrasts with graceful degradation, which starts with the full experience and tries to handle failures.

Accessibility (often abbreviated a11y) is the practice of designing and building websites and apps so they can be used by everyone, including people with visual, motor, auditory, or cognitive disabilities. This involves proper semantic markup, keyboard navigation support, sufficient color contrast, and screen reader compatibility. Beyond being an ethical responsibility, accessibility is increasingly a legal requirement in many jurisdictions.

The Virtual DOM is a lightweight in-memory representation of the actual browser DOM that React uses to optimize UI updates. When state changes, React creates a new Virtual DOM tree, compares it with the previous one through a process called reconciliation, and calculates the minimal set of real DOM mutations needed. This batching and diffing approach avoids expensive direct DOM manipulation and was a key innovation that made React's declarative programming model performant.

Infrastructure as Code (IaC) is the practice of managing and provisioning servers, networks, and cloud resources through machine-readable configuration files rather than manual processes. It enables version control, code review, and automated testing of infrastructure changes just like application code. Tools like Terraform, Pulumi, and AWS CloudFormation are popular IaC solutions that make environments reproducible and consistent.

Server-Side Rendering (SSR) is a technique where web pages are rendered to HTML on the server for each request, rather than relying on client-side JavaScript to build the page in the browser. SSR provides faster initial page loads and better SEO since search engines receive complete HTML content. Modern SSR in frameworks like Next.js supports streaming, allowing the server to progressively send HTML chunks as they become ready rather than waiting for the entire page to render.