Latitude North-South angle between our location, the center of the earth, and the equator. Equator is latitude 0, latitude increases in North and South directions to 90 degrees at the poles.
Lines of latitude are circles that run parallel to the equator.
Longitude East-West angle between our location, the center of the earth, and the Greenwich meridian. Greenwich is chosen as longitude 0 for historical reasons. Longitude is measured in the East and West directions, increasing to 180 degrees. All points at the same latitude. Small circles are parallel, and decrease in circumference as you move further North or South from the equator.