Infertility is characterized as the inability to conceive after a year of regular unprotected intercourse, with primary infertility being when no previous pregnancies occur and secondary infertility indicating a failure to conceive after a previous pregnancy. The causes of infertility are divided between male factors, female factors, or a combination of both, with various physiological and genetic issues impacting fertility. Treatment options include lifestyle changes, medical therapies, and assisted reproductive technologies, with legal and ethical considerations specific to artificial reproductive techniques in India.