Ceremonies are taking place around the world to mark the 20th anniversary of a landmark agreement protecting children. The UN says the Convention on the Rights of the Child has transformed the way children are treated. But it says a billion children in the world still go without food, shelter or healthcare and that millions are facing lives of poverty and abuse. On the eve of events, a British charity warned millions of the world's children have no parents or family around them. The Convention on the Rights of the Child , signed in 1989, guarantees children the right to life, to education, the right to play and to be protected from abuse.It has the widest international support of any human rights treaty – ratified by 193 countries, with only the US and Somalia yet to give their backing.