USB flash drives use NAND flash memory, which means that they’ll store your data even without power. When you’re ready to transfer content to or from your drive, just plug it into a compatible host device.

Your USB flash drive will draw the power it needs to store data directly from your computer, tablet, or smartphone — and you’ll be ready to move files onto and off your drive.

Here’s a quick guide to help you choose, from 64GB up to 1TB:

• 64GB: Basic backup of personal files like documents, casual photo collections, and some multimedia like music and video.
• 128GB: General backup of mid-sized multimedia libraries, including photos, videos, and music, plus gaming files and documents.
• 256GB: Partial system backup of large photo collections, video and music libraries, large gaming storage, and document archives.
• 512GB: Full system backups of large multimedia projects, software collections, and your largest gaming storage.
• 1TB: Extensive system backups for professional multimedia libraries, massive document files, and multiple large gaming saves.

USB flash drives are often categorized based on the host devices they attach to and what connectors they use with the host.

• USB-C™: For connecting your USB flash drive to your favorite USB Type-C™ devices, like the newest iPhone 15 generation or compatible tablets and computers.
• USB-A: For attaching your USB flash drive to devices with USB Type-A ports, like desktop computer towers or docking stations.
• Lightning: For using your USB flash drive with previous generations of Apple devices, like earlier iPhones, iPads, and Macs.

You’ll also need to make sure that your USB flash drive uses the right USB protocol for your host device. USB protocol generations include USB4, USB 3.2, USB 3.1, and more.

You can learn more about USB protocols at Thunderbolt vs. USB-C.

You can easily format a USB flash drive by plugging it into your computer, opening the drive, and clicking on Format for Windows® or Erase from Disk Utility for Mac.

However, the main thing you’ll need to decide is what file system to use for the formatting process.

Here’s a quick guide to your options:

• FAT32: Best for compatibility with both Windows® and Mac — but has a 4GB file size limit.
• NTFS: Good for Windows-only use, supports large files.
• exFAT: Suitable for both Windows® and Mac, supports large files.
• MacOS Extended (Journaled): Best for Mac-only use.

“Thumb drive” is another name for USB flash drives. “Flash drives,” on the other hand, are storage devices that use flash memory to store data — that includes everything from USB flash drives and solid state drives to microSD™ cards.

Occasionally, these terms are used interchangeably for USB flash drives, in addition to terms like “USB sticks” or “pen drives.”