Complementary and alternative medicines are two health approaches whose roots, in contrast to conventional medicine, are non-mainstream. The terms complementary and alternative have often been used interchangeably, though they do encompass two distinctive approaches to medicine. Complementary medicine refers to the use of non-mainstream approaches to medicine in conjunction with techniques from conventional medicine. On the other hand, alternative medicine refers to the use of non-mainstream approaches to medicine in replacement of techniques from conventional medicine.