Hair dryers can be classified into different categories based on their features and technology. Here are some of the most common types of hair dryers:

1. Ionic hair dryers: These hair dryers use negative ions to break down water molecules, which helps to dry hair faster and reduce frizz and static.
2. Ceramic hair dryers: These hair dryers use ceramic technology to distribute heat evenly, which helps to prevent hot spots and reduce damage to the hair.
3. Tourmaline hair dryers: These hair dryers use tourmaline technology to emit negative ions and infrared heat, which helps to reduce frizz and static while also adding shine to the hair.
4. Titanium hair dryers: These hair dryers use titanium technology to deliver high heat and fast drying, making them a popular choice for professional stylists.
5. Travel hair dryers: These hair dryers are compact and lightweight, making them easy to pack and take on the go.
6. Professional hair dryers: These hair dryers are designed for salon use and have a more powerful motor and advanced features, such as multiple heat and speed settings and various attachments.
7. Hooded hair dryers: These hair dryers have a hood that fits over the head, allowing for hands-free drying. They are often used in salons for deep conditioning treatments or roller sets.

By understanding the different types of hair dryers available, you can choose one that best suits your needs and hair type.