Templates let you write one piece of code that works with many types — a single `sort()` for integers and strings, or one `vector` class instead of separate `IntVector` and `StringVector` copies. This idea became the foundation for C++'s standard library (`vector`, `map`, `sort`).

Before templates, C++ libraries were either copy-pasted for every data type or written with unsafe void pointers. Templates made reusable, type-safe libraries practical.

Developers could ship one generic containerAn isolated runtime environment packaging an app and its dependencies — lighter than full virtual machines. or algorithm and reuse it across their whole codebase — with no runtime performance penalty.