The document discusses templates in C++. It defines a template as a keyword that allows functions or classes to operate on different data types without knowing the specific type. There are two types of templates: function templates, which define functions that can work with different data types, and class templates, which define classes that can work with different data types. Examples of templates include a function template to find the maximum of two numbers and a class template to add two values. Templates reduce code repetition and make the program more manageable.