A guitar is a stringed instrument you pluck or strum to make sound

A guitar belongs to the family of stringed instruments—machines that produce sound by vibrating strings. When you pluck or strum the strings with your fingers or a pick, they vibrate. Those vibrations travel through the body of the guitar, which amplifies them into the sound you hear. The pitch (how high or low the note is) depends on the thickness of the string, how tight it is, and where you press down on the neck.

Guitars are classified by how they produce and project sound. An acoustic guitar has a hollow wooden body that naturally amplifies the string vibrations—no electricity needed. An electric guitar has a solid or semi-hollow body and uses pickups (magnetic devices under the strings) to convert vibrations into electrical signals, which then travel to an amplifier. A classical guitar is acoustic but uses nylon strings instead of steel and is played with fingernails rather than a pick. Each type sounds different and is built differently, but all three are guitars because they share the same basic principle: vibrating strings create sound.

Key Takeaways

  • A guitar is a stringed instrument that produces sound when you pluck or strum its strings, causing them to vibrate.
  • Acoustic guitars have a hollow body that amplifies string vibrations naturally, while electric guitars use pickups and an amplifier to project sound.
  • Classical guitars use nylon strings and are played with fingernails, whereas steel-string acoustics and electric guitars are typically played with a pick or fingers.
  • The pitch of a note depends on string thickness, tension, and where you press down on the neck—the same principle across all guitar types.

How the acoustic guitar amplifies sound

An acoustic guitar's body is a wooden box with a large opening on the back. When you pluck a string, it vibrates. Those vibrations travel down through the bridge (the piece holding the string at the body end) and into the wooden top of the guitar. The wood itself vibrates in response, and because it is a large surface area, it pushes a lot of air around it. That moving air is what you hear as sound—louder than the string alone would be.

The shape and size of the body matter. A larger body moves more air and sounds louder. The type of wood also affects the tone—different woods vibrate at different frequencies and produce warmer or brighter sounds. This is why two acoustic guitars can sound noticeably different even if they are the same model, depending on the wood used and how it was dried and treated.

How the electric guitar uses pickups and amplifiers

An electric guitar does not rely on a hollow body to amplify sound. Instead, it uses pickups—coils of wire wrapped around magnets, positioned under the strings. When a steel string vibrates above a pickup, it disturbs the magnetic field, and that disturbance is converted into a tiny electrical signal. That signal travels through a cable to an amplifier, which boosts it and sends it to a speaker.

Because the signal is electrical, you can shape and change it before it reaches the speaker. You can add distortion, reverb, delay, or other effects. You can also control the volume with a knob on the guitar itself. This flexibility is why electric guitars are popular in rock, blues, and many other styles. The solid body of an electric guitar does not need to amplify sound naturally, so it can be thinner and lighter than an acoustic.

Classical guitars and nylon strings

A classical guitar is acoustic—it has a hollow wooden body—but it is built and played differently from a steel-string acoustic. The strings are made of nylon (the three lower strings have a wire winding wrapped around the nylon core), not steel. Nylon strings are softer and produce a warmer, mellower tone than steel strings.

Classical guitars are played with the fingernails or fingertips of your right hand, plucking individual strings in a specific pattern. You do not use a pick. The neck is wider and the strings are spaced farther apart, which makes fingerstyle playing easier. The body is also typically smaller and lighter than a steel-string acoustic. Classical technique and repertoire are formal and distinct—if you learn classical guitar, you are learning a specific tradition of playing and music.

The difference between pitch and tone

Two concepts often confuse new players: pitch and tone. Pitch is how high or low a note is. On a guitar, pitch is determined by which string you pluck and where you press down on the neck. Press down closer to the headstock (the top of the neck) and the string is longer, so the pitch is lower. Press down closer to the body and the string is shorter, so the pitch is higher. This works the same way on acoustic, electric, and classical guitars.

Tone is the color or character of the sound—whether it sounds bright, warm, mellow, harsh, or rich. Tone is affected by the type of wood, the strings, how hard you pluck, what part of the string you pluck, and (on an electric) what pickups and amplifier you use. Two guitars playing the same note at the same pitch can sound completely different because of their tone.

Why guitars are classified as chordophones

In music, instruments are organized into families based on how they make sound. Guitars belong to the family called chordophones—instruments that produce sound from vibrating strings. Other chordophones include banjos, mandolins, violins, harps, and pianos. All of them work on the same principle: a string vibrates, and that vibration becomes sound.

Within the chordophone family, guitars are further classified as plucked string instruments (as opposed to bowed instruments like violins, or struck instruments like pianos). This classification tells you something practical: you make the string vibrate by plucking it with your fingers or a pick, rather than by drawing a bow across it or striking it with a hammer.

Frequently Asked Questions

Is a guitar a percussion instrument?

No. A guitar is a stringed instrument, not a percussion instrument. Percussion instruments (drums, cymbals, xylophones) make sound by being struck. A guitar makes sound when strings vibrate, which is a different mechanism entirely.

Why do electric guitars need an amplifier?

Electric guitars produce only a tiny electrical signal from the pickups. That signal is too weak to hear at normal volume. An amplifier boosts the signal and sends it to a speaker, which converts it back into sound loud enough to hear. Without an amplifier, an unplugged electric guitar is very quiet.

Can you play an electric guitar without plugging it in?

Yes, but it will be very quiet—much quieter than an acoustic guitar. Some players practice this way to avoid disturbing others. The sound is thin and lacks the character an amplifier adds. For performance or recording, an amplifier is necessary.

What makes a classical guitar sound different from a steel-string acoustic?

Nylon strings vibrate differently than steel strings and produce a warmer, softer tone. Classical guitars are also built with different wood and bracing (internal supports) to match that sound. The playing technique—fingerstyle rather than pick—also affects the tone.

Do all guitars have the same number of strings?

Most guitars have six strings, but some have seven, eight, or twelve. Twelve-string guitars have pairs of strings tuned close together, creating a richer, fuller sound. Seven and eight-string guitars extend the lower range. The basic principle remains the same: vibrating strings make sound.