Freud first described transference in 1895, in his chapter on psychotherapy in the Studies on Hysteria, as a ‘false connection’: the patient attaches to the physician ideas that belong elsewhere.
In the postscript to the Dora case (1905) he traced the end of the treatment to a transference he had not mastered in time. By 1912 he saw transference as the most powerful resistance to treatment and, at the same time, the field on which the treatment had to be won; he distinguished positive from negative transference.
Later schools kept the term and changed what is transferred. For Melanie Klein it is a ‘total situation’ rooted in the earliest object relations; for Jacques Lacan it attaches to the analyst as the ‘subject supposed to know’; for Heinz Kohut narcissistic patients form mirror and idealizing transferences. The analyst's side of the relationship came to be studied as countertransference.