Template language is a programming construct that allows developers to create dynamic content that can be reused throughout an application. In Go, there are several popular template engines available, including html/template, pongo2, and mustache. These engines map template files to a set of data values, which is then used to render the final output.

The core of template language syntax is template tags, which are enclosed within delimiters, typically "{{" and "}}". These tags may include variable substitutions, loops, conditional expressions, and other constructs that allow for flexible and dynamic content generation.

Go's html/template engine provides a powerful set of built-in functions and features for generating HTML output, and it can be extended with custom functions to add additional functionality as needed. The template engine also includes support for template inheritance, which allows for the creation of a base template that is then extended or overridden by other templates as needed.

Pongo2, another popular template engine for Go, includes features like support for macros, custom filters, and template inheritance. It's designed to be fast and memory-efficient, making it a good choice for high-performance applications.

Finally, mustache is a flexible and lightweight template engine that can be used with a variety of programming languages, including Go. It's designed to be simple to use and easy to learn, making it a good choice for quick prototyping or small projects.

Overall, using a template language in Go can help developers create dynamic and scalable applications with powerful and flexible content generation capabilities.