Search engine indexing is the process where a page from your website will be added to the index of a search engine. Once a page/url has been added to this index, it will begin to appear in the search results. So how does a page make its way to the search index? How do search engines like Google gather the information from your website and know how to index it?
Search Engine Spiders
A spider, often referred to as a search engine crawler is a piece of automated software that runs as part of a search engine. This software will crawl around the web, visiting various websites, clicking links and analyzing the content on the website. For each page that the spider crawls, it will transmit all of the information it can, back to the likes of Google where it will be processed and added to the index.
How do I get a spider to crawl my website?
Web crawling is controlled and owned by the search engine itself. Whether they want to visit your website is up to them. If your website has lots of backlinks, you will likely get crawled fairly often as the crawler visits all of the links on a page (unless the website instructs a crawler not to).
If you have setup your domain inside Googles search console, you will be able to trigger the crawling process on demand, at least partially. If you paste a URL into the analyzer, it will check to see whether this URL has been added to Googles search index. If it has not, you will be able to submit it to the crawling queue. The page will normally be crawled in an hour or so.
Sitemaps are how spiders know how to access all of the pages on your website. While the general theory behind web design is that a crawler should be able to access every page on your website without a sitemap, having a sitemap is still critical. Creating an Xml sitemap is simple and most SEO plugins for your CMS do it automatically. All a sitemap does is list every single unique page on your website. A spider will download this from the web server when it visits and will crawl through these URLs.
Wasting Crawl Time
Google and other larger search engines will only allocate a set amount of time to crawl your website each day. If images are large and your server is slow, it can take several seconds for a page to load. The longer it takes for each page to load, the less web pages that will be crawled in the session. If you read further into the search engine indexing section of this guide, you will gain a better understanding of how to manage your websites crawl budget.