Modularization techniques in ABAP include:
1. **Subroutines (FORM)** - Reusable blocks of code that can be called multiple times.
2. **Function Modules** - Encapsulated functions that can be called from any program or other function modules.
3. **Methods** - Part of classes in Object-Oriented ABAP, allowing encapsulation and reuse of code.
4. **Includes** - Code segments that can be included in multiple programs to avoid redundancy.
These techniques are important because they promote code reusability, improve maintainability, enhance readability, and facilitate easier debugging.