SSI (Server Side Includes) is a server-based web page production technology, usually used to dynamically generate web page content. By using SSI instructions, text, graphics, or application information can be included into web pages, and this information can be dynamically generated and updated on the server side. Using SSI technology, instructions can be inserted into an HTML document that instruct the web server to insert certain content into the page before sending it to the client. For example, you can use SSI directives to include time/date stamps, copyright notices, or forms for customers to fill out and return. In addition, SSI also has some advanced functions, such as including files, executing shell and CGI script programs, etc. By using include files, you can put the content into a separate file and then just call that file in the HTML document, rather than typing the content into each file. This makes it easy to manage and maintain web content. In general, SSI is a powerful and flexible web page production technology that can help developers dynamically generate and update web page content on the server side, improving the performance and maintainability of the website.