The Hebrew particle et (H854) is a preposition meaning with, together with, beside, in company with. It is among the most frequent words in the Hebrew Bible and expresses proximity, accompaniment, or partnership. It should not be confused with H853 (et), the direct object marker.
The relational particle et carries deep theological weight. Genesis 5:22 says Enoch walked with God — the intimacy that defines genuine godliness. Joseph's success is attributed to God being with him (Genesis 39:2–3). The great covenant formula 'I will be with you' (Genesis 26:3; Exodus 3:12; Matthew 28:20) rests on this same concept of divine accompaniment. Immanuel — 'God with us' — is perhaps the ultimate theological expression of this tiny word.