Parallels of Latitude:
Parallels of latitude are imaginary lines that run parallel to the Equator. These lines are drawn on maps and globes to help locate places on Earth. They are measured in degrees, with the Equator being at 0 degrees latitude and the North and South Poles being at 90 degrees latitude.

Key Points:
- Parallels of latitude are horizontal lines that circle the Earth.
- They are used to measure the distance north or south of the Equator.
- The Equator is the largest parallel of latitude, dividing the Earth into the Northern and Southern Hemispheres.
- Other important parallels of latitude include the Tropic of Cancer, the Tropic of Capricorn, and the Arctic and Antarctic Circles.

Meridians of Longitude:
Meridians of longitude are imaginary lines that run from the North Pole to the South Pole. These lines are also measured in degrees, with the Prime Meridian being at 0 degrees longitude. The Prime Meridian runs through Greenwich, London, and serves as the reference point for calculating longitude.

Key Points:
- Meridians of longitude are vertical lines that intersect at the poles and connect points of equal longitude.
- They are used to measure the distance east or west of the Prime Meridian.
- The Prime Meridian divides the Earth into the Eastern and Western Hemispheres.
- Other important meridians of longitude include the International Date Line and the 180th meridian.

Relationship:
Parallels of latitude and meridians of longitude are both used to determine the exact location of a place on Earth. They work together on a coordinate system to create a grid-like pattern that helps in navigation, mapping, and understanding the Earth's surface. The parallels of latitude provide the horizontal reference, while the meridians of longitude provide the vertical reference. By combining these two measurements, one can pinpoint any location on Earth using a set of coordinates.

Conclusion:
Parallels of latitude and meridians of longitude are essential tools for understanding and navigating the Earth's surface. They work together to create a grid system that allows us to locate places accurately. Parallels of latitude measure the distance north or south of the Equator, while meridians of longitude measure the distance east or west of the Prime Meridian. By using these lines of reference, we can find our way around the world and understand the relationships between different locations.