4 Families of An Orchestra.

String

Woodwind

Brass

Percussion 

String: Violin, viola, double bass, harp

Generally the string family is categorized as the string because they are played in the particular way of the stick stroking the strings or strumming with the fingers. The instrument in the string family are made out of wood and for a certain period of time catgut was the most effective way to construct a violin, harp, cello etc. Musically instruments these days are made out of steel or polymer.

Woodwind: piccolo, flute, oboe, English horn, clarinet, E-flat clarinet, bass clarinet, bassoon and contrabassoon. 

The woodwind instruments are usually made out of wood or hallowed out reed and in rare cases it is made out of a metal. You play them by blowing air through the mouthpiece (that's the "wind" in "woodwind") and opening or closing the holes with your fingers to change the pitch. Metal caps called keys cover the holes of most woodwind instruments.

Brass: trumpet, French horn, trombone, and the tuba.

Brass instruments are made out of mental. Like the woodwind family, brass players use their breath to produce sound, but instead of blowing into a reed, you vibrate your own lips by buzzing them against a metal cup-shaped mouthpiece. The mouthpiece helps to amplify the buzzing of the lips, which creates the sound. Most brass instruments have valves attached to their long pipes; the valves look like buttons. When you press down on the valves, they open and close different parts of the pipe. You change the pitch and sound by pressing different valves and buzzing your lips harder or softer.

Percussion: timpani, xylophone, cymbals, triangle, snare drum, bass drum,tambourine, maracas, gongs, chimes, celesta and piano.

The percussion family is the largest in the orchestra. Percussion instruments include any instrument that makes a sound when it is hit, shaken, or scraped. It's not easy to be a percussionist because it takes a lot of practice to hit an instrument with the right amount of strength, in the right place and at the right time.