Let’s face the facts; you can’t play the guitar unless you know guitar tuning. Okay, so you have a kick-ass guitar that looks expensive but you couldn’t play it yet because it is out of tune. What shall you do when you don’t know how to tune it? This is why guitar tuning is a requirement for guitar players. What if you’re guitar is already tuned? It will still eventually go out of tune. Lots of factors affect the tuning of the guitar. The stings go out of tune when you, 1. Do a lot of bending, 2. Change in temperature, 3. Bumping your guitar, so on and so forth. So you should really learn how to tune your guitar.
There are different ways to tune your guitar. You can tune it using an electronic guitar tuner, a piano, a tuning fork or pitch pipe, from another tuned guitar, your phone or the internet. No matter which method you will use in tuning, always start below the note then up. The standard tuning is EADGBE. It is the most commonly used tuning. But there are also other guitar tunings like drop d (DADGBE), double drop (DADGBD) or Eb (EbAbDbGbGbEb) and drop Db 0r C# (DbAbDbGbBbEb).
The tunings are dependent to the song that you’ll be playing. If it requires lower notes, use a lower tuning. It all depends on you.