Here's a breakdown:

* Dominant allele: A version of a gene that masks the effect of the recessive allele.

* Recessive allele: A version of a gene that is only expressed if two copies are present.

Examples:

* Brown eyes: Brown eyes are dominant over blue eyes. So, an individual with one brown eye allele and one blue eye allele will have brown eyes.

* Widow's peak: A widow's peak hairline is dominant over a straight hairline. An individual with one widow's peak allele will have a widow's peak.

In summary:

* Homozygous dominant: Two copies of the dominant allele (e.g., BB for brown eyes). Offspring will have the dominant trait.

* Heterozygous: One copy of the dominant allele and one copy of the recessive allele (e.g., Bb for brown eyes). Offspring will have the dominant trait.

* Homozygous recessive: Two copies of the recessive allele (e.g., bb for blue eyes). Offspring will have the recessive trait.