Two-wave Indexing

Two-wave Indexing describes Google's approach to crawling and indexing web pages in two distinct phases. The first wave immediately processes the raw HTML content as delivered by the server, while the second wave occurs later after JavaScript has executed and rendered additional content.

This sequential processing creates a critical timing gap that can impact search visibility. Content that only becomes available after JavaScript execution—such as dynamically loaded text, images, or structured data—may be delayed in indexing or potentially missed entirely. This timing issue particularly affects AI Overview visibility, as Google's AI systems may only reference content available during the first indexing wave.

For JavaScript-heavy sites like SPAs and React applications, solutions include Server-Side Rendering (SSR), static site generation, or prerendering to ensure critical content appears in the initial HTML and gets indexed during the first wave.