Google displays a block of HTML code you can insert into your Web documents, which allows allow users to use the custom search engine directly from your website without leaving the page.

Semantic HTML 101 Semantic HTML elements provide meaning and structure to web content. It helps search engines and browsers better understand the content and relationships on the page.

Later search engines introduced so-called XML sitemaps meant to replace manual “search engine submission.” More than 25 years later, HTML sitemaps are less preferred.