What is the name of the 4th string?

The name of the 4th string on a standard-tuned guitar is indeed A. This string is often referred to as the "A string" and plays a crucial role in forming various chords and notes throughout the fretboard. Understanding the naming conventions of guitar strings is vital because it helps players identify the notes they are playing and enables them to navigate the fretboard more effectively.

In standard tuning, the strings are tuned to E (6th string), A (5th string), D (4th string), G (3rd string), B (2nd string), and E (1st string). Knowing that the 4th string is D is essential for tuning, playing chords, and chord progressions since many open chords and scales are based around this particular string. Additionally, the A string, being the 5th string, is often used in tonic chords and accented strumming patterns, further highlighting its importance to a guitarist's skill set.