Semichah is the Hebrew term for rabbinic ordination. It derives from lsmoch, meaning to touch or lean against something. The first person to receive semichah was Joshua: [Moses] took Joshua . . . and he laid his hands upon him and gave him a charge (Numbers 27:22).
The ritual of semichah symbolises both the transference of knowledge and authority from teacher to student and the readiness of the teacher to rely or lean on his students capabilities. In Talmudic times, semichah was a requirement for judging legal cases and could only be granted in the Land of Israel.
Later, the ritual of the placing of the hands was discontinued as the rabbis preferred to bestow semichah on their students either orally or in writing. In modern Hebrew, to be musmach means to be certified, as in: There are some crazy therapists out there; you should go to one whos musmach.
In the 19th century, the curriculum for semichah candidates underwent radical changes. The growing Reform movement wanted their rabbis to master subjects such as history and homiletics and de-emphasised Talmud and halachah.
In the late 20th century, the curriculum changed again to include counselling skills and psychology. Semichah became a professional qualification rather than a passing of spiritual authority.