What are the names of the 3 imaginary lines of the earth?

The Prime Meridian- Straight line, runs through Greenwhich, England, is 0 degrees longitude, splits the world into Eastern and Western Hemispheres.
The International Date Line- Much less of a Straight Line, runs through middle of the Pacific Ocean (Kind of), is where the day "switches" from one to another, but it is complicated. It's ends connect with the prime meridian, and is approximately 180 degrees in Longitude.

Equator- Straight Line running "perpendicular" to Prime Meridian. 0 degrees Latitude. Splits the world into Northern and Southern Hemispheres.

A couple more: Arctic Circle circles the North Pole at 66° 33' 44" North and Antarctic Circle at the same but South.