1. E (high): This is the thinnest string and is usually made of steel. It is tuned to the note E in the fourth octave (E4).
2. A: The second string is slightly thicker than the E string and is also made of steel. It is tuned to the note A in the third octave (A3).
3. D: The third string is thicker than the A string and is usually made of steel or nylon. It is tuned to the note D in the third octave (D3).
4. G: The fourth string is thicker than the D string and is made of steel or nylon. It is tuned to the note G in the third octave (G3).
5. B: The fifth string is thicker than the G string and is also made of steel or nylon. It is tuned to the note B in the second octave (B2).
6. E (low): This is the thickest string and is made of steel. It is tuned to the note E in the second octave (E2).
The gauges of the strings vary depending on the guitar's size and construction. Lighter gauge strings are easier to play but produce a softer sound, while heavier gauge strings have a brighter sound but are more difficult to play.