In biology, a trait or character is a feature of an organism.
The term phenotype is sometimes used as a synonym for trait in common use, but strictly speaking, does not indicate the trait, but the state of that trait (e.g., the trait eye color has the phenotypes blue, brown and hazel).
A trait may be any single feature or quantifiable measurement of an organism.
However, the most useful traits for genetic analysis are present in different forms in different individuals.
A visible trait is the final product of many molecular and biochemical processes.
In most cases, information starts with DNA traveling to RNA and finally to protein (ultimately affecting organism structure and function).
This information flow may also be followed through the cell as it travels from the DNA in the nucleus, to the Cytoplasm, to the Ribosomes and the Endoplasmic Reticulum, and finally to the Golgi Apparatus, which may package the final products for export outside the cell.
Cell products are released into the tissue, and organs of an organism, to finally affect the physiology in a way that produces a trait.