This is the 13402nd most frequent German word.
beitreten
"Beitreten" means "to join" or "to become a member of."
The verb 'beitreten' is used transitively with the dative case in German, indicating joining an organization or group.
Er möchte dem Verein beitreten.
He wants to join the club.
In this context, 'beitreten' means to participate in an activity or discourse.
Wir haben uns entschlossen, der Diskussion beizutreten.
We decided to join the discussion.
Here 'beitreten' refers to becoming a member of a group or community.