The other answers here are correct, but I wanted to add something: "Jr." is short for "junior." "Junior" means "younger." The opposite is "senior," which can be abbreviated as "Sr." For example, there used to be a baseball player named Ken Griffey. He had a son who shared his name. When the son became a baseball player, he was called Ken Griffey Jr. Because Ken Griffey Jr. was a better player, he became more famous than his father. Now, when people talk about his father, they refer to him as Ken Griffey Sr. so that people don't confuse him for his son.

Good question! Some people will place a "Jr." after their name to indicate they have the same name as their parent. For example: A father named Joe Johnson has a son. He and his wife agree to name him Joe Johnson. Unless he has a different middle name, he will likely go by Joe Johnson Jr. This will reduce confusion. If a neighbor says, I spoke with Joe, folks might wonder "Which Joe?". If they specify, "Oh, I spoke with Joe Jr.", then there is little confusion. Another real world example on the opposite side would be the two former U.S. presidents with the last name Bush. The father is George H.W. Bush. The son is George W. Bush. So, in this case he is not "JR." because there is a slightly different middle initial or name. I hope this helps.

If a person has the title "Jr" after their name, it means they have the same name as their father and the "Jr" is used to differentiate them.

Because his father has the same name that him!!!