i bought 1 TB external HD but it does not show external Drive on the iMac

If your brand new external hard drive isn’t showing up on your iMac, it likely needs to be formatted, here are the steps to format your external drive:

1. Connect the hard drive to your iMac.

2. Open the Disk Utility. You can find this by going to the “Finder”, then “Applications”, then “Utilities”, and finally “Disk Utility”. Alternatively, you can use the search function (Spotlight) to find it.

3. Once in Disk Utility, you should see a list of drives on the left. Your external hard drive should appear here. If it does, click on it.

4. Click on the “Erase” tab at the top of the Disk Utility window.

5. Here you can name your hard drive, choose the format, and the scheme. For most iMac users, you’ll want to choose “APFS” for the format. The scheme should be set to “GUID Partition Map”.

6. Click “Erase”. This will format the hard drive, erasing all data on it, and making it compatible with your iMac.

Remember, formatting your drive will erase all data on it, so ensure you don’t have any important data on the drive before you proceed.

If your hard drive still doesn’t show up in Disk Utility, there might be an issue with the drive itself, the cable, or the port on your Mac. You might need to contact Apple Support or the manufacturer of your hard drive for further help.

Have you formatted it using an Apple format? Many come formatted for Windows.