We have previously posted about how you can install the ADB and Fastboot tools in any Windows PC using Android SDK Tools, but many things have changed since then. Android SDK Tools has now become Android Studio for one, the latest Android SDK API has undergone many updates for two, and they have updated the versions of ADB and Fastboot tools as well. So if you want to install ADB and Fastboot in 2018, you do not have to follow the same multi-step instructions as before. Instead, you can now just run a small setup installer and it will install ADB and Fastboot on your system.
The good developers at XDA forums have created something called Minimal ADB and Fastboot installer. It is only 1 MB in file size and quickly installs ADB and Fastboot on your Windows system. When you launch the Minimal ADB and Fastboot installer it mentions that the tools have been downloaded straight from the GitHub page of ADB and Fastboot tools. In other words, it is going to install the very latest version of these tools on your Windows PC.
After the installation is done, you can open any command prompt in Windows and give the command ADB to see the various commands supported by ADB. You can also notice the version of ADB that has been installed is 1.0.39. Similarly, the Fastboot version that is installed is also the latest version.
If you have been using an older version of ADB or Fastboot for some time, you will notice that many things have changed in the new versions. You can update your knowledge of ADB and Fastboot by visiting the Android Studio help website at https://developer.android.com/studio/command-line/adb.html.
You can download Minimal ADB and Fastboot installer from XDA forums at https://forum.xda-developers.com/showthread.php?t=2317790.