https://www.musical-u.com/learn/how-to-tune-your-guitar-by-ear/
A lot of discussion can be had over whether the guitar should be tuned by ear or with the help of an electronic device. As we’re about to see, tuning by ear has multiple benefits over the “easier” path of using a tuner.
By the end of this guide on how to tune a guitar for beginners, you’ll know how to tune your guitar with just your hands and ears, popular alternate tunings, and how to check that you’ve tuned correctly by using a piano. https://www.musical-u.com/learn/how-to-tune-your-guitar-by-ear/