What is a "white lie"?

According to urban dictionary, a white lie is a lie told to prevent arguments or bad feelings over something. It is told to spare someone's feelings. It is a type of lie with good intentions. An example of this is given below.

Marian asked if I could come with her to Jesse's birthday party, Jesse and I are not in good terms so I told Marian a white lie that I have to be at a church program with my family.

This example shows that I do not want to attend the party and I do not want her to feel bad that I do not want to go the party so I had to tell her a white lie.