Diffusing while blow-drying curly hair is used to:

A diffuser attachment on a blow-dryer spreads the airflow over a wider area and reduces direct force, which helps dry curly or wavy hair while preserving and enhancing its natural curl pattern and reducing frizz. Blasting curly hair with concentrated high airflow tends to disrupt the curl and create frizz. Choosing tools and attachments suited to the hair type and goal is part of styling skill. Knowing the purpose of a diffuser is a practical hairstyling detail that can appear on the exam.