A more thorough explanation:

Definition: A father is a male parent.

Example: John is the father of Sarah.

This example illustrates that John is the male parent of Sarah. He is responsible for her upbringing and providing for her needs.

Acknowledged father: An acknowledged father is the biological father of a child born to unmarried parents.

Example: Tom is the acknowledged father of Emily, who was born to unmarried parents.

This example shows that Tom is the biological father of Emily, even though her parents were not married. He has acknowledged his paternity and is responsible for providing for her needs.