Infertility is defined as the failure to conceive within one or more years of regular unprotected intercourse. It can be caused by male factors in around 1/3 of cases, female factors in another 1/3 of cases, and both male and female factors in the remaining cases. Common causes include problems with sperm quality, ovulation, fallopian tubes, or general health issues. Treatments depend on the underlying causes and may include ovulation induction, surgery, assisted reproductive technologies like IVF, and lifestyle changes. Proper testing and counseling of both partners is important for diagnosis and management of infertility cases.