• <!--#include file="header.html"-->

• Executing Server Commands: With SSI, server commands can be executed to generate dynamic content. For example, you can display the current date and time.

• <!--#echo var="DATE_LOCAL"-->

• Environment Variables: SSI can display environment variables that contain information about the server, the request, or the user.

• <!--#echo var="REMOTE_ADDR"-->

• Conditional Statements: SSI supports conditional statements that allow content to be shown or hidden based on certain conditions.

Advantages of SSI:

• Reusability: Allows the reuse of HTML parts across multiple pages.
• Maintainability: Simplifies the maintenance of websites since common elements like headers and footers can be changed centrally.
• Flexibility: Enables the creation of dynamic content without complex scripting languages.

Disadvantages of SSI:

• Performance: Each page that uses SSI must be processed by the server before delivery, which can increase server load.
• Security Risks: Improper use of SSI can lead to security vulnerabilities, such as SSI Injection, where malicious commands can be executed.

SSI is a useful technique for creating and managing websites, especially when it comes to integrating reusable and dynamic content easily. However, its use should be carefully planned and implemented to avoid performance and security issues.