There are a couple possible ways of limiting ticket sales.
1. Simply specify the maximum amount of each ticket type that can be sold, e.g. 200 Adult tickets, 200 Child tickets etc. (This means you have a maximum of 400 tickets in total)
2. Create your ticket types and just below this section on the same edit/create page is the option called "Total Capacity". In this input field enter the value to limit the overall sales.
The ticket types governed by the Total Capacity ruling are:
- Paid tickets
- Free tickets
- Box-office collection
The ticket types not affected by the Total Capacity ruling are:
Note: This was moved from the Manage Event -> Attendees -> Capacity page in January 2019