We require all users to designate the month and year of their birth to verify age. VOMO requires all users to comply with the U.S. Child Online Privacy Protection Act, and does not allow anyone under the age of 13 to create their own account. (see section G, item 3, "Can I block children under 13 from my general audience website or online service?" in the link above)
The VOMO Platform also includes Age Requirements on many of the Projects. In our efforts to provide a safe platform for children and families while also allowing for volunteer projects that only people of a certain age can signup for, we require a birthdate for every single user in the platform with a minimum age of 13 years old when they create their account.