Diophantus was an ancient Greek mathematician, often referred to as the "father of algebra." He lived around the 3rd century AD and is best known for his work titled Arithmetica, which introduced methods for solving polynomial equations. His approach laid the groundwork for future developments in algebra and number theory. Diophantus focused on finding integer solutions to equations, a field now known as Diophantine equations. His contributions significantly influenced later mathematicians, including Fermat and Euler, and his techniques are still studied in modern mathematics.