Alternative versions of a gene that code for different variations of a protein
are called alleles.
You may inherit different alleles from your parents for any given trait, such as hair color.
Different alleles may result in the production of different proteins and be observed as different traits of an organism, such as petal color.
An observable trait is called a phenotype, while an individual's alleles make up its genotype (genetic makeup).
The genotype determines the phenotype.