Diophantus of Alexandria was a Greek mathematician active during the 3rd century AD, often referred to as the "father of algebra." He is best known for his work "Arithmetica," which introduced systematic methods for solving equations and laid the groundwork for future developments in algebra. Diophantus's contributions include symbolic notation and the study of Diophantine equations, which are polynomial equations that seek integer solutions. His work significantly influenced later mathematicians in both the Islamic Golden Age and the European Renaissance.