A USB drive must be formatted with a file system that the Raspberry Pi can read to work with the Raspberry Pi. The Linux file system Ext4 is the most popular choice for this use. You must perform the following steps to format a USB drive using Ext4 on a Raspberry Pi:- Step 1:- On the Raspberry Pi, attach the USB drive to a USB port. Step 2:- Enter the following command to list the accessible disk devices on the Raspberry Pi after opening a terminal window: sudo fdisk -l Including the USB drive, this command will show every disk drive attached to the Raspberry Pi. Note the USB drive's device name, which is typically something like /dev/sda. Step 3:- Use the following command to unmount the USB drive:- sudo umount /dev/sda Step 4:- Replace "/dev/sda" with the device name of your USB drive. Enter the next command to format the USB device with Ext4: sudo mkfs.ext4 /dev/sda Replace "/dev/sda" with the device name of your USB drive. Step 5:- Await the formatting process to be finished. Step 6:- Following formatting, the USB drive will be prepared for usage with the Raspberry Pi. Remember that formatting a USB drive will delete all of the data contained on the drive. Before you format the drive, back up any vital data. Use a program like Gparted to format the USB drive with the preferred file system if you prefer another one, such as NTFS or Fat32. But be aware that the Raspberry Pi might not entirely support some file systems, and you might encounter compatibility problems.