Vāgdāna / Sagāī — the engagement
Vāgdāna means “giving one's word”. The two families formally agree to the marriage, usually after matching horoscopes and fixing the wedding muhūrta. Gifts are exchanged, a tilak may be applied to the groom, and today rings are often exchanged.
It goes by many names — sagāī, roka, nishchitārtham, magni — but the heart is the same: two families publicly committing to each other.