I think everyone uses SD Cards or Micro SD Cards for all kinds of things. I use them in my DSLR and in an audio recorder. There are many other uses for them. Occasionally we need to format one of these little guys. Here is how you do that in the current iterations of macOS.
Formatting SD Cards
Some older Macs had SD Card slots. If you have a newer Mac without an SD Card slot, you need a SD Card Reader connected to your Mac via USB. The first thing to do in formatting an SD Card is mount it in your Mac. If you are formatting a Micro SD Card you need an Adapter like this:
You slip the Micro SD Card in that slot in the bottom and then insert the SD Card Adapter into your Mac.
Once the card is mounted in your Mac, start the Disk Utility Application from the Utilities Folder. You should see a window similar to this:
You will probably not have has many devices attached to your Mac as I do. You should be able to find the SD Card in the list of devices in the left sidebar. All you have to do is select it and click on “Erase”. You will be taken to this window:
Now comes the tricky part. If the SD Card you are formatting is 32GB or less, choose MS-DOS (FAT) under the Format menu drop down. If the SD Card is over 32GB, ExFAT is your formatting choice. Once you have chosen the correct Format option, just click “Erase” and the card is formatted. Please keep in mind this will erase all the stuff on the card.
You can format an SD Card with a Mac file system format. However, most SD Cards are used in devices like cameras, recorders, etc. In those devices, the SD Cards need to be formatted with a Windows friendly format. The Mac can read Windows formats and so can other devices.
You do not need to format a SD Card or Micro SD Card too often, but then you do it pays to do it right. Some day we will be using some newer type of storage format, but for now SD Card’s are ubiquitous.