Touch gestures in Microsoft Windows refer to actions performed on the touchscreen interface using specific finger movements. These gestures enable users to interact with their devices more intuitively and perform various tasks without relying solely on traditional input methods like a keyboard or mouse.

Here is a clear explanation of why the correct answer is "Perform actions using finger movements."

1. Understanding Touch Gestures: Touch gestures are designed to make interactions with devices more natural. They mimic real-world actions like swiping, pinching, and scrolling. For instance, a swipe gesture might scroll through a page, while pinching might zoom in or out.
2. Functionality: These gestures are specifically meant to enhance ease of use and efficiency. They allow users to quickly navigate through applications, access menus, and execute commands like opening files or switching between apps.
3. Comparison with Other Options:
   • Connect External Devices: This action typically requires physical connections or wireless technology (like Bluetooth or Wi-Fi) and doesn't directly relate to touch gestures.
   • Type Faster on the Keyboard: While touch keyboards exist, they do not inherently increase typing speed. Typing speed relies more on proficiency and familiarity with the keyboard layout.
   • Increase Screen Brightness: While a touch gesture could be set up to adjust brightness, it is not the primary purpose of touch gestures.

Thus, the main purpose of touch gestures is to facilitate user interaction through finger movements, providing a more fluid and direct way to manage actions on a touchscreen interface.