Normally the baby finger is not required while playing guitars.

Thumb (T) is used for plucking bass strings (D4, A5, E6)

Index (1) is used to pluck the string G3

Middle (2) is used to pluck the string B2

Ring (3) is used to pluck the string E1

However, for some advance guitarist, they are flexible to play the guitar with their own unique styles which they are comfortable with.

Acoustic guitars usually have six strings, although there are variations on this, the most common being a twelve-string guitar;

Guitar pick is used for strumming purpose at most of the time. It produces a clearer and sharper sound while strumming compared to your fingers. It comes with various thicknesses for different sharpness of sound.

Capo is used to clamp on the guitar's fretboard for higher keys. Example: Capo clamped on Fret number 2 gives 1 key higher. Means when you play C in this situation, the key is actually D.