Capacity controls how many places you'll sell. You can cap the whole event, cap an individual price type, or leave it unlimited.
Event capacity: a maximum number of places; leave off for unlimited.
Per-price limit: cap a single price type, useful for early-bird or VIP.
For a series, set a default capacity per session, or apply one limit across the whole block.
Bix allows organisations to turn on the 'spots remaining' banner to show how many places are left and create urgency.
Capacity can't be reduced below the places already booked - if Bix won't accept a lower number, check the current bookings first.