There are a few online resources that have images of different musical instruments that are available for different purposes, including Kids Picture Dictionary and Music With Ease. The Kids Picture Dictionary provides many images of instruments that are categorized by different types like strings, woodwind, brass and percussion.
At the Kids Picture Dictionary, there is a small dictionary of terms used in music that describe the different types of music, including blues, country, jazz and rock. This dictionary is geared towards young children so that they can learn about musical instruments. For example, there is a section where children can learn about the types of instruments played in an orchestra.
The Music With Ease website has an extensive listing of musical instruments and their pictures. People can search for a specific instrument either through the alphabetical or category lists that are provided. A brief description of the instrument and its origin are also given. For example, this online resources has pictures of instruments like the balalaika and koto, which are string instruments. The balalaika is an instrument played in Russia that has a triangular shape and three strings, and the koto is a Japanese 13-stringed instrument. This website also gives information and pictures on different composers as well as music quotes.