Learn Icelandic: Þau sjást og kyssast í dag. - They see each other and kiss today.

The -st ending creates the middle voice. In this sentence, it gives the verbs a reciprocal meaning, which means doing something to each other. If you used the active base verbs sjá (to see) and kyssa (to kiss), you would need to add an object. A listener would wait to hear who they are seeing and kissing! The -st ending packs the "each other" meaning right into the verb itself.

How do you form this -st ending for plural pronouns like þau?

For plural pronouns like við, þið, and þau in the present tense, it is very straightforward. The regular active forms for þau are simply the base verbs sjá and kyssa. To make them middle voice, you just attach -st to the end, giving you sjást and kyssast.

Why does this sentence use þau for "they" instead of þeir or þær?

Þau is the neuter plural pronoun. In Icelandic, you must use þau when referring to a mixed-gender group (for example, a man and a woman). You would use þeir only for a group of males, and þær only for a group of females.

Why is "today" written as two words (í dag)?