API
API is a set of rules that lets different software talk to each other. It's how your app asks another service for data or tells it to do something.
Definition
A set of rules that lets different software talk to each other. It's how your app asks another service for data or tells it to do something.
Example
When your app shows the weather, it's calling a weather API to get that data.
Related Terms
More Web Development Terms
SSR - Server Side Rendering
The server builds the full HTML page before sending it to the browser. Great for SEO and fast initial loads because users see content immediately instead of a blank screen.
CSR - Client Side Rendering
The browser downloads a minimal HTML shell, then JavaScript builds the page. Fast subsequent navigations, but users might see a loading spinner on first visit.
Hydration
When server-rendered HTML gets "activated" by JavaScript in the browser. The page looks ready instantly, then becomes interactive once the JS loads and attaches event listeners.
SPA - Single Page Application
A web app that loads once and never does a full page refresh. Navigation feels instant because it just swaps content instead of requesting new HTML from the server.
MPA - Multi Page Application
The traditional web model where each page is a separate HTML document. Click a link, server sends a new page. Simple, reliable, and SEO-friendly out of the box.