particle
inwards (prefix), into the inside / inward
B1
herein- is a separable particle/prefix meaning 'inwards' or 'into the inside', indicating movement toward the speaker. Used with verbs (e.g. hereinkommen, Komm herein!). Contrasts with 'hinein-' (movement away). Functions as a modal directional particle, not an independent verb; attaches to verbs and separates in finite forms.
Examples
Er trug die Kisten herein.
He carried the boxes inside.
Komm herein!
Come in!
Der Lehrer rief die Schüler herein, weil die Stunde pünktlich beginnen sollte.
The teacher called the students in because the lesson was to start on time.
Details
Mnemonics
An arrow pointing into a box, indicating movement inside
Sounds like English 'here in' — think 'come here in'
Notes
herein- is a directional prefix/affix denoting movement inward; it appears in separable verbs (e.g., hereintragen). In everyday speech you also see the adverb 'herein' in commands like 'Komm herein!'.