Infertility refers to the inability to conceive after one year of unprotected sex or to maintain a pregnancy, and it can stem from various causes in both men and women. Women's infertility can be caused by issues like blocked fallopian tubes, irregular periods, and uterine problems, while men's infertility may result from sperm production issues or abnormal sperm quality. Management options include sperm banking, surrogacy, hormone therapy, and advanced reproductive technologies such as in-vitro fertilization.