There are four different instrument families, that consist the following: Brass, woodwind, percussion, and finally the stringed family. They are all major components in a orchestra. An orchestra can't really be an orchestra without any of these types of instruments. To finally summarize what orchestra is, well it's a group of instrumentalists combining their respective types of instruments into one harmony.
The first I'll be talking about is the brass family. Well the brass family is a family of instruments that consists of the trumpet, tuba, any variation of the horn, trombone, and finally the cornet. These instruments produce pitches by changing the valves, and latches. They also produce music by blowing into which then produces a symphonic vibration which then goes through a resonator, and finally produces music in sync with the performers lips.
The percussion family is a pretty broad family, with most of the instruments being different variations of the drum. It consists of the piano, conga, any variation of the drum, xylophone, cymbals, and the marimba. These instruments are considered the oldest of all the families. They produce sound by being struck by with a beater, or even scraped.
The woodwind is basically divided by flutes, and reed like instruments. But, they consist of the ocarina, flute, piccolo, oboe, clarinet, reed pipes and finally a saxophone. They produce music in different ways, but I'll be explaining how most of them do it. They blow into a sharp edge which is made to split the air stream then produces a sound or pitch. Its kinda like whistling.
The string family is comprised of the harp, guitar, ukulele, banjo, and finally the cello. These string instrument produce music by getting plucked, stricken by a hammer, or even by being rubbed by a bow. These instruments are just a fraction of the whole thing. The string family is the broadest of all the families.