Online Guitar Tuner - Standard Tuning
This is the "normal" and most popular tuning for a guitar. It's also most likely to be the tuning your guitar is setup for.
Standard tuning has evolved to give a good compromise between easy fingering of most common chords and straightforward fingering of scales.
If you are going to play along with other musicians, your tuning will need to match theirs. This tuning will be what you should go for as they will most likely be tuned in standard tuning also.
If you are just playing on your own, it's good practice to use standard tuning to get used to the "feel" of the guitar setup this way.
When reading tab music where no tuning is noted, you can be fairly sure standard tuning is what you should be using.
Standard tuning is recommended for beginners.
Most guitarists will use standard tuning most, or at least some of the time.
Standard tuning is the highest in pitch most guitars will get tuned to. To get to this high pitch the strings have to be put under a fair bit of tension. This tension can make string bending difficult so it's recommended to use light gauge strings. These are strings where the thinnest string or 1st string is 0.08 or 0.09 inches. The lighter the gauge of string the less tension is needed to get it to a given pitch. Therefore bending the string becomes easier.
Lighter strings will die faster after been picked (they have less sustain) than heavier strings. Turning up the gain should help compensate for this.
Note: If you want to tune higher than standard tuning, it is recommended you use a capo instead. Otherwise you risk strings breaking and excessive strain on the guitar neck.
If you are having problems with your strings "buzzing" on the frets when you play notes, it may be because your guitar is tuned to flat. This causes the neck of the guitar to straighten, which can cause the buzzing. If you prefer to tune down your guitar you may need to get it setup differently to cater for this.
Note: String buzzing can be caused by a number of other factors including worn frets, incorrect truss-rod setup and incorrectly adjusted string height. If in doubt contact your nearest guitar shop.