Ma'anar ƙamus na "ƙara jini" shine tsarin jigilar jini daga wani mutum zuwa wani. Ana yin wannan yawanci azaman magani don maye gurbin jinin da ya ɓace saboda rauni ko tiyata, don kula da wasu yanayin kiwon lafiya waɗanda ke shafar ikon jiki don samarwa ko kula da isassun matakan ƙwayoyin jini, ko don haɓaka lafiya da walwala gabaɗaya. Karan jini na iya zama ko dai ta atomatik, wanda mutum zai karbi jininsa da aka bayar a baya, ko kuma allogeneic, wanda mutum ya karbi jini daga mai bayarwa mai dacewa.