If you are interested in singing, you probably have one or more favorite singers. A large part of what attracts us to a particular singer’s voice is the way it sounds rather than the notes the singer uses. Every singer has an individual sound because everyone’s anatomy is slightly different.
Just as each person has a different height, weight, arm and leg length, skin tone etc, we all have slightly different shapes, sizes and thicknesses of the parts of the body involved in singing. The lungs, windpipe, larynx, tongue, lips, and cavities in the mouth and behind the nose are all individual and combine to create a particular timbre (tonal quality or tone color).