A USB adapter is used to convert one type of USB port into another, allowing different devices with varying USB connectors to connect and communicate, expanding compatibility, and facilitating data transfer, charging, and other functions between devices. 

USB adapters come in various types to provide versatile connectivity options. Some common types include:

1. USB-C to USB-A Adapter: Connect USB-C devices to USB-A ports, providing compatibility with older USB devices.
2. USB-C to HDMI/DisplayPort Adapter: Connect your USB-C device to an HDMI or DisplayPort-enabled display or projector, enabling high-definition video output.
3. USB-C to Lightning Adapter: Allowing charging and data transfer between USB-C devices and Apple devices with Lightning ports, such as iPhones and iPads.
4. USB-C to Ethernet Adapter: Add an Ethernet port to your USB-C device, providing a stable and fast wired internet connection.

Yes, USB adapters can affect data transfer speeds depending on the type and quality of your adapter and the compatibility with the connected devices. High-quality USB C to USB adapters that support the latest USB 3.1 standard can provide faster data transfer speeds compared to older or low-quality adapters while using other adapters may only transfer at its permitted speed. 

In most cases, USB adapters do not require additional drivers. They are designed to be plug-and-play and work automatically when connected to a compatible device. Besides, modern Windows, macOS, and Linux operating systems may have built-in drivers to support a wide range of USB cable adapters. However, there might be some exceptions where certain specialized or older USB adapters may require specific drivers to function correctly.