1. Access Control: Tickets help regulate entry to the event by confirming that attendees have purchased or been granted access. They prevent overcrowding and ensure that only authorized individuals can participate.

2. Organization and Crowd Management: By assigning specific ticket types (e.g., general admission, VIP, or reserved seating), event organizers can better manage the flow of guests, direct them to appropriate areas, and maintain order during the event.

3. Revenue Generation: Tickets are a primary source of revenue for most events. They allow organizers to monetize the event, whether through sales, donations, or different pricing tiers.

4. Branding and Promotion: Custom-designed tickets can serve as a promotional tool, featuring the event’s branding, sponsors, or partners. They can also act as collectibles, adding to the attendee’s experience.

5. Tracking and Data Collection: Tickets provide a way to track the number of attendees, which helps with event planning, budgeting, and future marketing strategies. Digital tickets also allow for easy collection of data like attendee preferences.

6. Legal and Liability Protection: Tickets often contain terms and conditions that help limit the organizer's liability. They also provide a record of attendance, which may be useful in case of disputes or insurance claims.

In essence, tickets are not only essential for controlling access and generating revenue, but also play a critical role in the overall organization and experience of the event.