The ibbur only makes full sense placed beside its two companion concepts, gilgul and dybbuk, since Lurianic Kabbalah treats all three as different points on a single spectrum describing how a soul that has left one body can relate to another living body, distinguished mainly by consent, permanence and moral character. Gilgul describes a full new incarnation, a soul reborn into a new person from birth to correct or complete unfinished spiritual work across an entire lifetime; ibbur describes a temporary, welcomed visitation for a specific, limited purpose; and dybbuk describes an unwelcome, often punitive attachment by a soul in genuine spiritual distress.
Later Hasidic literature developed the ibbur concept further, with some accounts describing revered teachers or tzaddikim as receiving the ibbur of an earlier sage's soul at moments of particular need, lending the recipient temporary access to that sage's wisdom. Because the ibbur is a benevolent, structurally different phenomenon from a dybbuk, folklore and popular treatments of Jewish possession belief that collapse the two terms together, as sometimes happens in film and fiction borrowing the word for horror purposes, misrepresent a distinction the Kabbalistic sources themselves treat as fundamental.