Functions and class templates in programming provide a powerful way to write reusable and generic code. Function templates allow developers to define a single function that works with any data type, reducing redundancy and improving flexibility. Similarly, class templates enable the creation of generic classes that can handle different data types or behaviors without rewriting code. These templates are parameterized, meaning developers can specify the type when instantiating them. Commonly used in C++ and other languages, templates are integral to creating type-safe, efficient, and scalable solutions, such as container classes, algorithms, and utility functions.