user78323: I am working on a project where I need to log data, but I was wondering if it is possible to log that data to a thumb drive? I know that I can log data to an SD card, but I thought a thumb drive would be more accessible to users who wish to obtain the data. And if it is possible to log to a thumb drive, could it be done in CSV format?
The data is just sensor data.

user31105: In principle you can log to a thumb drive any data you want, binary and text (thus also CSV).
However, the Arduino Uno does not support connecting a USB stick directly. If you want to connect a USB stick, you need a so called USB Host shield (for Arduino).
More information can be read on the Arduino site at this page:
https://docs.arduino.cc/retired/shields/arduino-usb-host-shield

user71575: [Updated]
As an alternative to a Uno host shield, changing to a different Arduino MCU may also assist. USB host capabilty is needed for communicating with thumb drives.
Some Arduino models have a native USB port (e.g., Arduino Due, Arduino Leonardo, Arduino Micro, Arduino Nano 33 IOT, Arduino Zero, Arduino MKR Zero, Arduino MKR1000 ... ) which will work as a USB client device role.
A smaller set of MCU can act as either a USB client or host (e.g., Arduino Due, Arduino Portenta, ...). There is a USBHost library for Arduino Due listed in the Arduino Reference. Documentation for Arduino Portenta in USB host mode is here.
Here is a discussion (and reference to an alternative library) regarding using a Due to write files to a thumb drive.
Of course an adapter cable or a thumb drive with a physical connector matching the native USB port on the selected MCU is required. Both are commonly available.
See also Can the Arduino interface with USB devices without the USB host shield?

78323: <p>I am working on a project where I need to log data, but I was wondering if it is possible to log that data to a thumb drive? I know that I can log data to an SD card, but I thought a thumb drive would be more accessible to users who wish to obtain the data. And if it is possible to log to a thumb drive, could it be done in CSV format?
The data is just sensor data.</p>
 31105: <p>In principle you can log to a thumb drive any data you want, binary and text (thus also CSV).</p>
<p>However, the Arduino Uno does not support connecting a USB stick directly. If you want to connect a USB stick, you need a so called USB Host shield (for Arduino).</p>
<p>More information can be read on the Arduino site at this page:</p>
<p><a href="https://docs.arduino.cc/retired/shields/arduino-usb-host-shield" rel="nofollow noreferrer">https://docs.arduino.cc/retired/shields/arduino-usb-host-shield</a></p>
 71575: <p>[Updated]</p>
<p>As an alternative to a Uno host shield, changing to a different Arduino MCU may also assist. USB host capabilty is needed for communicating with thumb drives.</p>
<p><a href="https://forum.arduino.cc/t/how-to-tell-if-a-board-has-native-usb-support-for-a-midi-project-with-a-mac/667494" rel="nofollow noreferrer">Some Arduino models</a> have a native USB port (e.g., Arduino Due, Arduino Leonardo, Arduino Micro, Arduino Nano 33 IOT, Arduino Zero, Arduino MKR Zero, Arduino MKR1000 ... ) which will work as a USB client device role.</p>
<p>A smaller set of MCU can act as either a USB client or host (e.g., Arduino Due, Arduino Portenta, ...). There is a <a href="https://www.arduino.cc/reference/en/libraries/usbhost/" rel="nofollow noreferrer">USBHost</a> library for Arduino Due listed in the Arduino Reference. Documentation for Arduino Portenta in USB host mode is <a href="https://docs.arduino.cc/tutorials/portenta-h7/usb-host" rel="nofollow noreferrer">here</a>.</p>
<p><a href="https://forum.arduino.cc/t/usb-host-due-support-for-mass-storage-devices-thumbdrives/635331" rel="nofollow noreferrer">Here</a> is a discussion (and reference to an alternative library) regarding using a Due to write files to a thumb drive.</p>
<p>Of course an adapter cable or a thumb drive with a physical connector matching the native USB port on the selected MCU is required. Both are commonly available.</p>
<p>See also <a href="https://arduino.stackexchange.com/questions/24177/can-the-arduino-interface-with-usb-devices-without-the-usb-host-shield">Can the Arduino interface with USB devices without the USB host shield?</a></p>
