Dutch aspect distinguishes between actions viewed as ongoing processes and actions viewed as completed wholes. The imperfective perspective (ongoing, habitual, or repeated) uses the present tense, imperfect, or aan het construction: “Ik werkte” (I was working / I used to work). The perfective perspective (completed, viewed as a whole) uses the perfect or pluperfect: “Ik heb gewerkt” (I worked / I have worked — completed).
The choice between imperfect and perfect for past events follows a key principle. Use the perfect for completed actions that are relevant now or for recent events in informal speech: “Ik heb gisteren gewerkt”. Use the imperfect in formal narrative and writing, especially for states, habitual actions, and the background of a story: “Het was een stormachtige nacht. Hij stond bij het raam en keek naar buiten.”
Understanding aspect also explains why certain verbs prefer one tense over the other. State verbs (zijn, hebben, weten, wonen, heten) naturally favor the imperfect in past narrative because they describe ongoing conditions rather than completed events. Action verbs favor the perfect in spoken Dutch. Developing a feel for this distinction — through extensive reading of Dutch prose — is what separates intermediate from advanced Dutch fluency.