What It Is
Indexing is the step where a search engine adds a page to its giant library, called the index. After crawling a page, Google reads its content, works out what it is about and decides whether to store it. Only indexed pages can show up in search results. If crawling is a librarian finding a new book, indexing is cataloging it and putting it on the shelf.
Why It Matters for Your Business
If a page is not indexed, it cannot be found through search, no matter how good it is. A salon might launch a new page for bridal hair and wonder why nobody finds it, only to discover Google has not indexed it yet, or that a "noindex" setting was accidentally left on. Checking indexing is one of the first steps when traffic is lower than expected.
Good to Know
Tip: in Google Search Console, use the URL Inspection tool to see whether a specific page is indexed and to request indexing after you publish or update it. Search engines do not index every page they find. Thin, duplicate or low-value pages are often skipped, so focus on useful, original content.