Definition
React is a popular JavaScript library for building user interfaces, often used to create fast, app-like websites. Instead of reloading the whole page, React updates only the parts that change, which can make a site feel smooth and responsive. Because it builds much of the page with JavaScript, how and when that content appears matters a lot for search.
Use Cases
React is used to build interactive sites and web apps, from dashboards to online stores, where parts of the screen update without a full reload. It is a common choice for teams that want a modern, component-based way to manage complex interfaces.
Why It Matters for SEO
React matters for SEO because content built only in the browser can be slow for crawlers to see, so many React sites use server side rendering or incremental static regeneration to deliver finished HTML. Getting this right affects how quickly and reliably your content is indexed. Handled poorly, JavaScript rendering can hide pages from search entirely.
Related Concepts
Related concepts include server side rendering, HTML rendering, and hydration. Each describes how a JavaScript-heavy site turns its code into pages that both people and crawlers can read.