Nonprofit events are primarily for the purpose of fundraising for a nonprofit agency and its programs.
The key with nonprofit events is for the planner to understand that your business is for-profit. While catering and convention service businesses are quite benevolent and can donate some of their profits, they must cover food and labor costs.
Nonprofit groups can include a wide range of organizations to include but not limited to:
Medical: research and development, patient assistance, health care centers, specialized education
Education: sororities, fraternities, alumni, affinity school programs
Community Outreach: human rights groups, ...