Why is it said that the Sun does not set in the Arctic Circle?

Can you imagine seeing the Sun at midnight?

Well if you were to visit the arctic circle in summer, you would see just that1 why does this happen?

You know that the earth’s axis is tilted, and because of this, one pole is inclined towards the sun for six months of the year, and the other pole for the rest of the year. The result is that the pole facing the sun has almost continuous day light for those six months, while pole facing away has almost continuous darkness during that period. 

In the case of the Arctic Circle there is almost continuous daylight during summer and almost continuous darkness during winter. In fact, on June 21st, sun does not set at all, and can be seen even at midnight.