In Hebrew grammar, the qal is the simple paradigm of the verb.
The Classical Hebrew verb conjugates according to person and number in two finite tenses, the perfect and the imperfect. Both of these can then be modified by means of prefixes and suffixes to create other "actions" of the verb. This is not exactly parallel to any categories of grammatical voice or mood in the Indo-European languages, but can produce similar results. So the niphal is effectively a passive, the piel is an emphatic form and the hithpael has a middle or reflexive force. The qal is any form of the finite verb paradigm which is not so modified.