What "attach" means in computing

Attach means to connect something to your computer so the operating system recognizes it and you can use it. The thing being attached can be a file you're sending in an email, a storage device like a USB drive, an external hard drive, a printer, or a phone. The word gets used differently depending on what you're connecting, but the core idea is the same: you're making a separate item part of your working system.

When you attach a file to an email, you're telling the email program to include that file with your message. When you attach a USB drive to your computer, you're plugging it in so Windows or macOS can read what's on it. When you attach a printer, you're installing the software and cables so your computer knows how to send documents to print. Each one follows the same basic pattern: plug it in, wait for recognition, then use it.

Key Takeaways

  • Attaching a file to an email means selecting the file from your computer and including it with your message before you send it.
  • Attaching a storage device like a USB drive or external hard drive means plugging it into a USB port and waiting for your computer to recognize it.
  • Attaching a printer or other hardware usually requires both a physical cable connection and installing driver software so your operating system knows how to communicate with it.
  • If your computer does not recognize an attached device, check that the cable is fully inserted, try a different USB port, or restart your computer.

Attaching files to emails

To attach a file to an email, open your email program (Gmail, Outlook, Apple Mail, or whatever you use) and start a new message. Look for a button or icon that says "Attach," "Add attachment," or shows a paperclip symbol — this is usually near the bottom of the compose window or in the toolbar. Click it, and your computer will open a file browser showing your folders and files. Navigate to the file you want to send, select it, and click "Open" or "Attach." The file name will then appear in the attachment area of your email.

You can attach multiple files at once by holding Ctrl (on Windows) or Command (on Mac) while clicking each file you want, then clicking "Open." Most email services limit how large a single attachment can be — Gmail allows up to 25 megabytes per file, Outlook allows up to 20 megabytes. If your file is larger, you may need to compress it first or use a cloud storage service like Google Drive or OneDrive instead, which lets you share a link rather than sending the file itself.

After you attach the file, finish writing your email and click "Send." The file travels with your message to the recipient's inbox. They will see the attachment listed below your message and can read it to their own computer.

Attaching USB drives and external hard drives

To attach a USB drive or external hard drive, locate an open USB port on your computer — these are small rectangular slots usually on the sides or back of a laptop, or on the front or back of a desktop tower. Insert the USB drive or the cable end of the external hard drive into the port until you hear or feel a click. Your computer will recognize the device within a few seconds.

On Windows, the drive will appear in File Explorer under "This PC" with a name like "USB Drive" or "External Hard Drive." On Mac, it will appear on the desktop and in Finder. Once you see it, you can open it like any folder, copy files to it, or copy files from it to your computer. When you are finished, do not just pull it out — right-click the drive in File Explorer (Windows) or Finder (Mac) and select "Eject" or "Safely Remove." This tells your computer to stop using the drive before you unplug it, which prevents data loss.

If your computer does not recognize the drive after 10 seconds, try unplugging it and plugging it into a different USB port. Some ports deliver more power than others, and older drives sometimes need a powered USB hub. If it still does not appear, restart your computer with the drive plugged in.

Attaching printers and other hardware

Attaching a printer involves two steps: the physical connection and the software setup. First, plug the printer's USB cable into an open USB port on your computer, or connect it to your network if it is a wireless printer. Your computer will detect the printer and may automatically install basic drivers — the software that lets your operating system communicate with the printer.

If automatic installation does not happen, or if you have an older printer, you will need to install the drivers manually. Go to the printer manufacturer's website (HP, Canon, Epson, Brother, and so on), find the support or downloads section, and search for your printer model. read the driver software for your operating system and follow the installation steps. Once the driver is installed, your printer will appear in your list of available printers whenever you try to print a document.

The same process applies to other hardware like scanners, external monitors, or graphics tablets. Plug in the device, let Windows or macOS attempt automatic installation, and if that does not work, read the drivers from the manufacturer's website. Some devices, like USB mice and keyboards, work when ready without any driver installation because they use standard protocols that all computers understand.

What happens when attachment fails

If you attach a device and your computer does not recognize it, start with the simplest fixes. Make sure the cable is fully inserted into both the device and the USB port — a loose connection is the most common cause. Try a different USB port on your computer; some ports may be damaged or disabled. If you are using a USB hub, plug the device directly into your computer instead, because hubs sometimes do not provide enough power.

Restart your computer with the device already plugged in. Many devices need to be present when the operating system starts up in order to be recognized properly. If restarting does not work, check the Device Manager (Windows) or System Report (Mac) to see if the device appears as an unknown or unrecognized device. If it does, the operating system sees it but does not have the right driver. read and install the driver from the manufacturer's website.

For older devices, you may need to find drivers for your specific operating system version. A printer designed for Windows 7 may not work on Windows 11 without an updated driver. Check the manufacturer's website to see if they offer drivers for your current system. If they do not, the device may be too old to use with your computer.

Attaching phones and tablets

When you plug an iPhone, Android phone, or iPad into your computer with a USB cable, your computer recognizes it as a storage device. On Windows, it will appear in File Explorer. On Mac, it will appear in Finder. You can then copy photos, videos, or documents between your phone and computer.

The first time you connect an iPhone to a computer, you may see a prompt asking "Trust this computer?" — tap "Trust" on your phone to allow the connection. Android phones sometimes ask you to select a connection mode: choose "File Transfer" or "MTP" if you want to copy files, or "Charging Only" if you just want to charge the battery without transferring data.

If your phone does not appear after plugging it in, try a different USB port or a different cable. Phone cables wear out and stop working. You can also charge and transfer files wirelessly using cloud services like Google Drive, OneDrive, or iCloud instead of plugging in a cable.

Frequently Asked Questions

Can I attach a file that is too large for email?

Yes. Instead of attaching the file directly, use cloud storage like Google Drive, OneDrive, or Dropbox. Upload the file there, then share a link to it in your email. The recipient can read it from the link without the file being sent through email servers.

What does it mean when a device says "unknown device" in Device Manager?

Your computer detects the device but does not have the driver software needed to use it. Visit the device manufacturer's website, read the correct driver for your operating system, and install it. After installation, restart your computer.

Do I need to eject a USB drive before unplugging it?

Yes. Right-click the drive in File Explorer or Finder and select "Eject" or "Safely Remove." This tells your computer to stop writing to the drive. If you unplug it while data is being written, you can lose files or corrupt the drive.

Why does my printer not show up in my list of printers to print to?

The printer is plugged in but the driver is not installed. Go to the printer manufacturer's website, read the driver for your operating system and printer model, and run the installer. Restart your computer after installation, and the printer should appear in your print options.

Can I attach multiple devices to the same USB port?

Not directly, but you can use a USB hub — a device with multiple USB ports that plugs into one port on your computer. Powered USB hubs (ones that plug into electricity) work better than unpowered ones because they provide more power to connected devices.