This past weekend was Orphan Sunday, a day many Christians and churches set aside to recognize God’s call that we defend the fatherless, care for the child that has no family, and visit orphans in their distress. Here are nine things you should know about orphans in America and around the world.

1. A common assumption is  that an orphan is a child who has two deceased parents. But the more inclusive definitions used by adoption and relief agencies tend to focus on a child who is deprived of parental care. An orphan can be further classified by using definitions such as UNICEF’s  “single orphans,” which is a child with only one parent that has died, or “double orphans,” which is a child who has two parents that are deceased. Under U.S. immigration law, an orphan can also be a foreign-born child with a sole or surviving parent who is unable to provide for the child’s basic needs, consistent with the local standards of the foreign sending country, and has, in writing, irrevocably released the child for emigration and adoption. The majority of the world’s orphans have families who are merely unable or unwilling to care for the child.

2. According to UNICEF estimates, there are 17,900,000 orphans who have lost both parents and are living in orphanages or on the streets and lack the care and attention required for healthy development.

3. In the U.S. 400,540 children are living without permanent families in the foster care system. 115,000 of these children are eligible for adoption, but nearly 40% of these children will wait over three years in foster care before being adopted.

4. According to the U.S. State Department, U.S. families adopted 8,668 children from another country in 2012 (compared to 22,991 in 2004). Last year, Americans adopted the highest number of children from China, Ethiopia, Russia, South Korea, and Ukraine.

5. Children raised in orphanages have an IQ 20 points lower than their peers in foster care, according to a meta-analysis of 75 studies (more than 3,800 children in 19 countries).

6. Each year, over 27,000 youth “age out” of foster care without the emotional and financial support necessary to succeed. Nearly 25% of youth aging out did not have a high school diploma or GED, and a mere 6% had finished a two- or four-year degree after aging out of foster care.

7. As of 2011, nearly 60,000 children in foster care in the U.S. are placed in institutions or group homes, not in traditional foster homes.

8. The average length of time a child waits to be adopted in foster care is over 3 years. Roughly 55% of these children have had three or more placements. One study found that 33% of children had changed elementary schools five or more times, losing relationships and falling behind educationally.

9. A study by the Rand Corporation found that as of April 11, 2002, a total of 396,526 embryonic humans have been frozen and placed in storage in the United States. Most of them will live and die in an IVF clinic. That is almost 400,000 orphans whose names we will never know and whose faces we will never see.