Glossary of Terms:

1/4-inch jack

A 1/4-inch socket commonly used on electronic musical instruments and professional audio equipment; A mono 1/4-inch jack uses two conductors (tip/sleeve), and a stereo 1/4-inch jack uses three conductors (tip/ring/sleeve).

Source: Yamaha

Also refered as:   TRS   TS   mono jack   phone jack   stereo jack

Related terms:   1/4-inch plug   XLR connector   balanced   headphones   input   output   unbalanced