You can find the Raspbian Buster download here. There are three options to choose from: Raspbian Buster with desktop and recommended software, Raspbian Buster with desktop, Raspbian Buster Lite. Any of these options will work for this guide.
Choose Raspbian Buster with desktop (or Raspbian Buster with desktop and recommended software) if you want to have access to the Raspbian GUI (graphical user interface); in other words, if you want to log in and be able to access a desktop, icons, etc. like you would with Windows or macOS.
Choose Raspbian Buster Lite if you're comfortable working on the command line and your project doesn't require a GUI. This option is typically for more advanced users, and it's often a good choice as it's a smaller distribution, uses less power, and fewer resources.
You'll likely need an adapter as most computers don't include a Micro SD slot.
By far the easiest way to flash Raspbian Buster onto your SD card is to use Etcher.
To get started, download and open Etcher. Select the Raspbian disk image you just downloaded, select your Micro SD card, then click Flash. This will take a few minutes, but after Etcher finishes, you're ready to start using Buster!
If you prefer a manual installation, keep reading.
With the Raspbian Buster image downloaded and your SD card inserted into your Mac, it's time to flash the disk image.
Open Disk Utility and find your SD card
To open Disk Utility, in Finder navigate to Applications > Utilities > Disk Utility. If you're SD card is inserted correctly, it should appear on the left hand side of the application.
Format the SD card
Click on the name of the SD card in the left column of Disk Utility.
Click the "Erase" button.
Choose a name for the card (any name will do as long as you can remember it), then choose MS-DOS (FAT) for the format.
Click Erase to complete the process.
Determine the mount point
df command (in Terminal) we're going to determine the mount point.
In the output, under the Mounted on column look for the name of your SD card. I named my BUSTER so I'm looking for /Volumes/BUSTER.
Then take note of the filesystem name in the first column. Mine is /dev/disk2s1. This is actually the partition name, but what we're really concerned with is the device name which is disk2. Copy this device name.
Unmount the volume
For this step you can use either Disk Utility or Finder. In either case look in the left column for the name of your SD card, and click the eject symbol.
Locate the Raspbian Buster disk image
By default, your disk image should be in your Downloads folder. We're going to use Terminal to find the disk image, unzip, and get the name of the img.
cd ~/Downloads ls -lha | grep -i buster
You should see output like this:
[Downloads]$ ls -lha | grep -i buster -rw-r--r--@ 1 tyler staff 346M Nov 8 14:51 2019-06-22-raspbian-buster-lite.zip
This will create a new file called 2019-06-22-raspbian-buster-lite.img.
Flash the disk image
Still in Terminal, type:
sudo dd bs=1m if=DISK_IMAGE_NAME of=DEVICE_NAME
Make sure to replace the values for DISK_IMAGE_NAME and DEVICE_NAME. Mine looks like this:
sudo dd bs=1m if=2019-06-22-raspbian-buster-lite.img of=/dev/rdisk2
Enter your password, and wait. After the process completes, you're done!
Note: You may have noticed that we're using rdisk2 instead of disk2. You can actually use either, but rdisk2 is significantly faster.
Format the SD card
Open Windows Explorer and find your SD card. Right click on the icon and click Format.... Make sure Fat 32 (default) is selected and hit enter.
Download and launch the Win32 Disk Manager
Go here and download the app called Win32 Disk Imager. After downloading the program, click to uncompress the files, and then click Win32DiskImager.exe to launch.
Flash the SD card
In the Win32 Disk Imager, click the blue folder icon and locate the Buster image you downloaded. Then in the Device box make sure the drive letter for your SD card is selected.
Click the Write button to begin.
If you're already running Raspbian (presumably "Stretch") on your Raspberry Pi, you can upgrade without having to go through the steps listed above.
To upgrade to Raspbian Buster, run the following command:
grep -rl stretch /etc/apt/ | sudo xargs sed -i 's/stretch/buster/g'
Once that finishes running, run the following command:
sudo apt update && sudo apt dist-upgrade
Finally, reboot your Pi:
Important: Raspbian has been replaced by Raspberry Pi OS! Raspbian is a free Debian-based operating system optimized for the Raspberry Pi, and Stretch is the development code name for Debian 9.