Cohabitation and Child Well-Being

Why do people cohabitate/what is cohabitation? What is Child Well Being? Are children of cohabitating parents
generally happy? Do children with cohabitating parents suffer more mental illnesses than those with married
parents? Do children with cohabitating parents have poor physical health compared to those with married
parents? Are children with cohabitating parents neglected more or less than those with married parents?