Aspect is a grammatical category

A basic aspectual distinction is that between perfective and imperfective aspects (not to be confused with perfect and imperfect verb forms; the meanings of the latter terms are somewhat different). Perfective aspect is used in referring to an event conceived as bounded and unitary, without reference to any flow of time during it ("I killed him"). Imperfective aspect is used for situations conceived as existing continuously or repetitively as time flows ("I was killing him"; "I used to kill people"). Further distinctions can be made, for example, to distinguish states and ongoing actions (continuous and progressive aspects) from repetitive actions (habitual aspect).