The guitar has become one of the most popular instruments in music today. Its use in rock, jazz, blues, country and folk music, as well as classical music, has made the guitar the instrument of choice for both students and adult players. Playing a few notes and chords on the guitar is easy to learn, although becoming a really good player will require years of practice and close attention. The fact that the guitar can be played at many levels of skill is surely one of the reasons for its popularity.

The first question is the best age for a child to begin to learn the guitar. Unlike wind instruments, the guitar does not require well-developed lungs or a complete set of permanent teeth. However, a full-size guitar is usually too large for a young child. Many children begin with a half size instrument as early as six years old. Three quarter size instruments are available for older children or adults with small hands. These have a shorter and narrower neck and are easier for a beginner to play. “Student” guitars are usually a little smaller than a standard full size instrument. By their early teens, most players are ready to graduate to a regular guitar.

This full-size instrument can be either an acoustic or an electric guitar. The fingering of all of the notes and chords is exactly the same, so it doesn’t matter which one someone learns on. Electric guitars will have steel strings and usually an amplifier, although the amplifier is not necessary for a student. They also have a longer neck. An acoustic guitar can be played with an electric pick-up, for added volume.
Acoustic guitars can have either steel or nylon strings. Steel string guitars are usually played in rock and country music and have a bright, metallic sound. Nylon string guitars have a more mellow sound and are used for classical and folk music, and some Latin music. Whichever one you choose, your fingers will get sore when you begin to play, but will toughen up in a few weeks. Its best, then, to choose the guitar based on what music you wish to play. The strings are not interchangeable between the two kinds of guitar, because the neck and bridge of a steel string guitar need to be specially reinforced to stand the greater tension of the steel strings. Never put steel strings on a guitar designed for nylon strings; the guitar will be seriously damaged. 
A student should learn something about playing the guitar, practice and become comfortable with the instrument, before thinking about joining a band. But once the player has developed some facility, a band can be terrific fun and pay some money too.

In a band, the guitar that plays the melody lines, and takes the solos, is called the lead guitar. Lead guitar is played with a standard electric guitar, or a steel-string acoustic. Professional guitarists experiment to create a variety of special effects with the electric guitar and with the amplifier. 

Supporting the lead guitarist is usually a rhythm guitarist who may be playing a bass guitar. A bass guitar has a longer neck than a standard guitar and usually has four strings, but may have as many as six. These are typically tuned to the same pitches as the double bass, which correspond to the pitches of the lowest four strings of a standard guitar, but one octave lower. The bass guitarist lays down the beat for the rest of the band and provides much of the harmony. Since the chords are a little different for the bass guitar, and the frets are farther apart, moving from a standard guitar to a bass guitar will be a learning experience.