Most guitars consist of six strings. The modern guitar developed from earlier stringed instruments like the lute. By the 16th century, the ADGBE tuning (same as the top five strings of the modern guitar) was commonly used. Following constant experimentation and technological advancements, the body and design was modified to improve volume and tone. Around mid 1800s, the modern six-string classical guitar design was born with six strings and EADGBE tuning.
Why EADGBE? The short answer is that the standard tuning is the most practical and comfortable way for your hands to play both chords and melodies
The name of the thickest string, the sixth string, is E. Moving on, the fifth string is A, fourth is D, third is G, second is B, and then the first string is E.