Tamar is a significant figure in the Book of Genesis, specifically in chapters 38. She was the daughter-in-law of Judah, one of the twelve sons of Jacob. After her husband, Er, died, Tamar was denied the opportunity to marry his brother, Onan, as was customary. Instead, she took matters into her own hands to secure her lineage. To ensure her rights, Tamar disguised herself as a prostitute and encountered Judah. This led to the birth of twins, Perez and Zerah. Tamar's actions highlight themes of justice and the importance of family lineage in biblical narratives.